History of Mexico
From the Olmec's colossal stone heads to a modern republic, told through the conquest that ended one empire and the revolution that remade the nation twice
Mexico's deep past belongs to the Olmec, Teotihuacan, the Maya, and the Aztec, each with a detailed timeline of its own here. This one picks up the national thread: Cortes and the fall of Tenochtitlan in 1521, three centuries of Spanish colonial rule built on silver and forced Indigenous labor, the 1810 revolt that took eleven years to become independence, the loss of half the country's territory to the United States, a civil war over the power of the Catholic Church, a French-installed emperor executed by firing squad, a 34-year dictatorship, and the 1910 revolution whose constitution still governs Mexico today. Every event is drawn from institutions fetched and checked directly: the Library of Congress's own exhibition on the Mexican Revolution, the U.S. National Archives, the Office of the Historian, the CDC, and university and museum sources.
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- Peer-reviewed4 events
- Reputable source9 events
- General source2 events
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Events
- c. 1200 BCEWell documented
Reputable source · 2 sourceswhy?
Best source: Introduction: The Origin and Development of Olmec Research
The domain "doaks.org" is on our Reputable source registry.The Olmec Build San Lorenzo and Carve the Colossal Heads
On Mexico's Gulf Coast, the Olmec built the earliest major civilization in Mesoamerica, centered on San Lorenzo and later La Venta, between about 1200 and 400 BCE. Their signature works are the colossal stone heads: seventeen have been found so far, ten at San Lorenzo and four at La Venta, ranging from about 1.47 to 3.4 meters tall and weighing up to 25 tons each. Workers carved each head from a single basalt boulder quarried in the Tuxtla Mountains and moved it, likely by river raft and log rollers, over distances that could exceed 100 kilometers. Each face is individual rather than generic, which is why most scholars read the heads as portraits of specific rulers rather than gods or generic ancestors.
Why it matters: The Olmec gave later Mesoamerican cultures, including the Maya and the Aztec, shared elements they built on for two thousand years: the ballgame, jaguar imagery tied to political power, and monumental civic architecture. The scale of the heads also proves organized labor and long-distance transport existed in Mexico a millennium before writing does.
How we know: The colossal heads have been excavated since the first was found in 1871, with the most recent recovered in 1994; their basalt has been sourced geologically to specific quarries in the Tuxtla Mountains, which is how archaeologists reconstruct the transport routes.
Region: Gulf Coast lowlands, modern Veracruz and Tabasco · Key sites: San Lorenzo, La Venta, Tres Zapotes · Heads found: 17 total (10 at San Lorenzo, 4 at La Venta) · Material: Single-boulder basalt, up to 25 tons
- c. 100 BCE - 550 CEWell documented
Reputable source · 2 sourceswhy?
Best source: Teotihuacan
The domain "worldhistory.org" is on our Reputable source registry.Teotihuacan Rises as the Largest City in the Pre-Columbian Americas
Teotihuacan formed in the Basin of Mexico between 150 BCE and 200 CE and grew into the largest city in the pre-Columbian Americas, reaching a population as high as 200,000 at its height between 375 and 550 CE. Its builders raised the Pyramid of the Sun around 100 CE over a natural cave and spring, a structure 215 meters per side and 60 meters tall, and the smaller Pyramid of the Moon around 150 CE, connected by the 40-meter-wide, 3.2-kilometer Avenue of the Dead. Around 600 CE the city's major buildings were deliberately burned and its religious sculptures smashed, and the identity of the people who built and ran it is still unknown: even the name Teotihuacan is not theirs. It is Nahuatl, given centuries later by the Aztec, and means 'place of the gods.'
Why it matters: The Aztec who arrived in the Basin of Mexico centuries after Teotihuacan's fall found its pyramids already ancient and treated the ruins as the place where the gods created the current era of the world, folding a vanished city into their own religion. Teotihuacan set the template, the pyramid-and-avenue city plan, that later Mesoamerican capitals including Tenochtitlan echoed.
How we know: Excavations at the Pyramid of the Sun found a 100-meter tunnel beneath it leading to a four-chambered space, and dedicatory offerings of obsidian and greenstone carvings recovered from the Pyramid of the Moon date its construction phases; the identity of Teotihuacan's original inhabitants remains an open question because they left no deciphered written language.
Region: Basin of Mexico, northeast of modern Mexico City · Peak population: Up to 200,000 (c. 375-500 CE) · Pyramid of the Sun: 215m per side, 60m tall, built c. 100 CE · Decline: Major structures burned c. 600 CE
- c. 250-900 CEWell documented
Reputable source · 2 sourceswhy?
Best source: Maya Civilization
The domain "worldhistory.org" is on our Reputable source registry.The Maya Build Rival City-States Across the Southern Lowlands
South and east of the Basin of Mexico, in what is now southern Mexico, Guatemala, Belize, and Honduras, the Maya built dozens of independent city-states rather than a single empire, sharing a writing system, a calendar, and a pantheon while warring with each other for centuries. Tikal and Calakmul, the two most powerful Classic-period kingdoms, fought a rivalry that shaped the political map of the Maya lowlands for over a century. The southern lowland cities went into a still-debated collapse between about 800 and 900 CE, while northern Yucatan cities and Maya culture generally continued for centuries afterward, ending only when Spanish forces took the last independent Maya city, Nojpeten, in 1697.
Why it matters: The Maya's deciphered glyphs are the only Mesoamerican writing system that lets modern scholars read pre-Columbian history in the words of the people who lived it, rather than through later colonial-era retellings. This civilization has its own detailed timeline on this site covering the Preclassic megalopolis at El Mirador, the Tikal-Calakmul rivalry, and the collapse debate.
How we know: Decipherment of Maya hieroglyphic writing, substantially completed in the late 20th century, lets historians read royal inscriptions directly rather than relying only on archaeology or Spanish colonial accounts.
Region: Southern Mexico, Guatemala, Belize, Honduras · Political structure: Dozens of independent, often warring city-states · Last independent city: Nojpeten, fell 1697
Sources- World History Encyclopedia. Maya Civilization · reference
- World History Encyclopedia. Tikal · reference
Related timelines- The Maya Civilization → · The full Maya story: the Mirador Basin megalopolis, the Tikal-Calakmul rivalry, decipherment, and the still-debated collapse.
- c. 1325 CEWell documented
Reputable source · 2 sourceswhy?
Best source: Tenochtitlan
The domain "worldhistory.org" is on our Reputable source registry.The Mexica Found Tenochtitlan and Build the Aztec Empire
The Mexica, a migrant clan who arrived at Lake Texcoco with no territory of their own, founded Tenochtitlan around 1325 CE on a marshy island, building it into a planned city of causeways and floating garden plots (chinampas) that grew to more than 200,000 people. Through the Triple Alliance formed in 1428 with Texcoco and Tlacopan, the Mexica built an empire that took tribute from hundreds of city-states across central Mexico, reaching its height under Moctezuma II before the Spanish conquest ended it in 1521.
Why it matters: Tenochtitlan's ruins became the foundation, literally, of Mexico City, and the Aztec tribute network Cortes exploited by allying with subject city-states is what made the conquest possible with a few hundred Spaniards. This civilization has its own detailed timeline on this site.
How we know: Much of what is known about the Aztec comes from post-conquest Spanish chronicles and from Aztec accounts recorded after 1521, so population and tribute figures carry real uncertainty and are treated as such on the dedicated Aztec Empire timeline.
Founded: c. 1325 CE, Lake Texcoco · Triple Alliance formed: 1428 CE · Peak population (Tenochtitlan): Over 200,000 · Fell to Spanish forces: 1521 CE
Sources- World History Encyclopedia. Tenochtitlan · reference
- World History Encyclopedia. The Fall of Tenochtitlan · reference
Related timelines- The Aztec Empire → · The full Aztec story: migration from Aztlan, the Triple Alliance, Moctezuma II, and the 93-day siege that ended the empire.
- 22 April 1519Well documented
Reputable source · 2 sourceswhy?
Best source: Hernan Cortes
The domain "worldhistory.org" is on our Reputable source registry.Cortes Lands at Veracruz and Gains Malinche as Interpreter
Hernan Cortes departed Cuba in February 1519 with eleven ships, about 500 soldiers, 100 sailors, and 16 horses, landing first at Tabasco in March. There, local leaders gave his expedition gifts including twenty enslaved women, one of whom, a multilingual Nahua woman named Malintzin (later called La Malinche or Dona Marina), became his interpreter and, eventually, the mother of his son. Fluent in both Nahuatl and Chontal Maya, she went on to learn Spanish and gave Cortes a communication channel into Aztec politics that no previous expedition had. Cortes landed at Chalchihuecan on 22 April 1519, Good Friday, and founded the settlement of Veracruz there, naming himself captain general to bypass the authority of Cuba's governor. He then ordered his ships deliberately grounded and broken up, removing the option of retreat, before marching inland toward Tenochtitlan.
Why it matters: Malintzin's translation and political advice let Cortes negotiate alliances with Aztec tributary states, especially Tlaxcala, whose warriors would outnumber the Spanish by more than a hundred to one at the siege of Tenochtitlan two years later. Without her, the small Spanish force had no way to exploit the resentments inside the Aztec tribute system.
How we know: Contemporary Spanish accounts, including chroniclers who traveled with Cortes, describe the Tabasco encounter, the founding of Veracruz, and the scuttling of the ships; the events are corroborated across multiple independent 16th-century sources.
Departure: Cuba, February 1519 · Force size: 11 ships, c. 500 soldiers, 100 sailors, 16 horses · Veracruz founded: 22 April 1519 · Key figure: Malintzin (La Malinche), interpreter
SourcesRelated timelines- The Age of Exploration → · See the wider Age of Exploration timeline for how Cortes's expedition fit into Spain and Portugal's global voyages.
- 13 August 1521Well documented
Peer-reviewed · 2 sourceswhy?
Best source: Megadrought and Megadeath in 16th Century Mexico
Cited as a "journal" source (no stronger domain match).Tenochtitlan Falls After a 93-Day Siege
Cortes began the siege of Tenochtitlan in April 1521 with roughly 700 infantry, 118 crossbowmen and harquebusiers, 86 horses, and 18 field guns, deploying thirteen purpose-built brigantines onto Lake Texcoco on 28 April to cut the city off. His decisive advantage was Tlaxcalan and other Indigenous allies, at least 100,000 strong, fighting alongside a Spanish force that was small by comparison. A smallpox epidemic in the preceding months had already killed much of the Aztec leadership and civilian population; the Spanish, for whom the disease had long been endemic, were largely unaffected. Spanish columns entered the city from three directions on 22 May, and after 93 days of fighting, starvation, and exhausted supplies, the last Aztec emperor Cuauhtemoc was captured trying to flee by canoe and surrendered on 13 August 1521. Tenochtitlan was sacked, looted, and its temples and monuments destroyed.
Why it matters: The fall of Tenochtitlan ended the Aztec Empire and gave Spain the city it would rebuild, on the same ruins and the same lake-bed foundations, as the capital of New Spain and eventually of modern Mexico. The scale of the human cost, a functioning capital of hundreds of thousands reduced by war, starvation, and epidemic disease within months, set the pattern for the demographic collapse that followed across the rest of the century.
How we know: Spanish military accounts detail troop numbers, the brigantine campaign, and the date of surrender; the smallpox epidemic's role is documented independently in both Spanish and Nahua sources describing mass death in the city before the final assault.
Siege began: April 1521 · Spanish forces: c. 700 infantry, 86 horses, 18 field guns · Indigenous allies: At least 100,000 Tlaxcalans and others · Surrender: 13 August 1521, Cuauhtemoc captured
SourcesRelated timelines- The Aztec Empire → · The full siege, day by day, on the dedicated Aztec Empire timeline.
- The Age of Exploration → · See how the conquest of Mexico fit into Spain and Portugal's broader age of exploration and conquest.
- 18 August 1521 - 1535Well documented
Primary source · 2 sourceswhy?
Best source: Map of Mexico in 1825
The domain "loc.gov" is on our Primary source registry.Mexico City Rises on Tenochtitlan's Ruins as the Capital of New Spain
Days after Tenochtitlan's surrender, Cortes founded Mexico City on the Aztec capital's ruins, and its cabildo, or town council, was formally chartered in 1522, making it the administrative seat of Spanish power in the region. The Kingdom of New Spain was proclaimed on 18 August 1521, but its permanent administrative structure, the Viceroyalty of New Spain, was not established until a royal decree on 12 October 1535 formalized rule by a crown-appointed viceroy based in Mexico City. At its territorial peak New Spain stretched from California and the present-day U.S. Southwest through all of Central America except Panama.
Why it matters: Mexico City's location directly atop Tenochtitlan, built using the same lake-bed and often the same stones as Aztec temples, meant Spanish colonial rule was constructed literally on the physical remains of the empire it replaced. The viceregal system created in 1535 became the template for how Spain governed the rest of its American empire.
How we know: Spanish colonial administrative records document the 1521 proclamation and the 1522 cabildo charter, and the 1535 royal decree establishing the viceroyalty survives in Spanish crown archives.
Mexico City founded: August 1521, cabildo chartered 1522 · Kingdom of New Spain proclaimed: 18 August 1521 · Viceroyalty formally established: 12 October 1535 · Peak extent: California to Central America (minus Panama)
- c. 1521-1523Well documented
Primary source · 2 sourceswhy?
Best source: MEXICO THE COLONIAL ERA
The domain "catdir.loc.gov" is on our Primary source registry.The Encomienda System Extends Forced Indigenous Labor Into Mexico
The encomienda, a medieval Spanish institution that entrusted a landowner with labor from those who worked his land in exchange for protection, had already been extended to the Americas from 1502 and received royal approval in 1503; Cortes brought it to Mexico immediately after the conquest, granting himself an encomienda of over 23,000 family units, far larger than the roughly 2,000-family grants typical elsewhere. Under the system, an encomendero received the right to indigenous labor and tribute in exchange for supposedly providing physical protection and Christian instruction. A junta in Spain moved to forbid new encomiendas as early as 1523, and reformers like Bartolome de las Casas pushed to abolish the system and make Indigenous people free vassals of the crown, but encomiendas persisted in practice for two centuries, with the last new grants ending only in 1721.
Why it matters: The gap between the encomienda's stated purpose, protection and conversion, and its reality, extraction of labor under threat of force, is why the system is now understood as a legal cover for what amounted to slavery. Its abuses, combined with epidemic disease, drove the population collapse that reshaped colonial Mexico's entire economy and social structure.
How we know: Spanish colonial legal records document both the granting of encomiendas, including the exceptional size of Cortes's own grant, and the contemporaneous debates among Spanish reformers and the crown over the system's abuses.
Extended to the Americas: From 1502 (Hispaniola); royal approval 1503 · Cortes's own grant: Over 23,000 family units · New Spain population, 1500 to 1550: c. 22 million to c. 3 million · System formally ended: 1721
- 9-12 December 1531Well documented
Primary source · 2 sourceswhy?
Best source: Great Miracle of the Apparition of the Queen of Heaven... Near the Great City of Mexico in the Place called Tepeyacac
Cited as a "primary" source (no stronger domain match).The Virgin of Guadalupe Appears at Tepeyac
Between 9 and 12 December 1531, an Indigenous convert named Juan Diego Cuauhtlatoatzin reported that the Virgin Mary appeared to him at Tepeyac hill, just outside Mexico City, a site that Spanish chronicler Bernardino de Sahagun recorded had previously held a temple to the Aztec mother goddess Tonantzin. When the local bishop demanded proof, Juan Diego is said to have gathered roses growing on the hill despite the winter season and carried them in his cloak, or tilma; when he opened it before the bishop, an image of the Virgin had appeared imprinted on the fabric. The bishop ordered a church built on the site, the beginning of what is now the Basilica of Guadalupe, and the tilma itself has survived for centuries.
Why it matters: The image placed the Virgin's shrine directly over a former Tonantzin temple and used Nahuatl in the reported dialogue, giving Indigenous Mexicans a path into Catholicism that did not require abandoning existing devotional geography. Historians describe the result as a bridge between Aztec religious tradition and Spanish Catholic imagery, and the Virgin of Guadalupe became, and remains, the central symbol of Mexican national and religious identity.
How we know: The earliest known written account of the apparitions in Nahuatl, held today at the Library of Congress, describes the events at Tepeyac between 9 and 12 December 1531; Sahagun's separate ethnographic writings independently confirm Tepeyac's prior status as a Tonantzin shrine.
Location: Tepeyac hill, near Mexico City · Reported dates: 9-12 December 1531 · Central figure: Juan Diego Cuauhtlatoatzin · Feast day: 12 December
- 1546-1550Well documented
Reputable source · 2 sourceswhy?
Best source: The Silver of the Conquistadors
The domain "worldhistory.org" is on our Reputable source registry.Silver Strikes at Zacatecas and Guanajuato Fund a Global Empire
Spanish prospector Juan de Tolosa found silver at Zacatecas in 1546, and the mines began operation under Spanish control by 1547-48, making Tolosa the richest man in New Spain. Guanajuato's mines opened in 1550 and eventually surpassed Zacatecas, with the Valenciana mine there producing about 30% of the world's silver supply at its late 18th-century peak. Mining silver at this scale required industrial infrastructure: a single facility at Sombrerete ran 84 stamp mills to crush ore and 14 furnaces to smelt it, and a mercury-based amalgamation process introduced around 1560 became the standard extraction method. By 1600, Spanish America was producing ten times as much silver annually as all of Europe combined.
Why it matters: Silver from Zacatecas and Guanajuato became the financial backbone of the Spanish empire and, through the Manila galleon trade, connected Mexico directly to Chinese and broader Asian markets, making New Spain a hub of a genuinely global economy two centuries before industrialization. The wealth also built the churches, universities, and colonial architecture that still define both mining cities today.
How we know: Colonial mining and tax records document silver output at both sites; UNESCO recognizes the Historic Centre of Zacatecas as a World Heritage Site specifically for its role in this mining history.
Zacatecas discovered: 1546, operational 1547-48 · Guanajuato discovered: 1550 · Valenciana mine (Guanajuato), peak: c. 30% of world silver supply · Spanish American silver output by 1600: 10x Europe's total production
- 1519-1600Debated
Peer-reviewed · 2 sourceswhy?
Best source: Megadrought and Megadeath in 16th Century Mexico
Cited as a "journal" source (no stronger domain match).Epidemic Disease Collapses Mexico's Indigenous Population
The smallpox epidemic that arrived with the Spanish in 1519 to 1520 is estimated to have killed roughly half the Indigenous population of central Mexico. Two further epidemics of a disease called cocoliztli, from 1545 to 1548 and again from 1576 to 1578, killed an estimated combined total of 7 to 17.5 million more people, up to 80% of the remaining Indigenous population in the first wave alone. Researchers who reanalyzed the 1545 and 1576 outbreaks found they were probably native hemorrhagic fevers rather than smallpox, carried by a rodent host and worsened by the most severe drought to hit north-central Mexico in 600 years, which concentrated stressed rodent populations near malnourished, drought-stricken human settlements. Mexico's population, estimated at 15 to 30 million before contact, had fallen to around 2 million by 1600.
Why it matters: This is one of the largest population collapses in recorded history, and it happened within living memory of the conquest itself: it emptied the labor base the encomienda system depended on, reshaped land ownership as Indigenous communal lands went vacant, and permanently altered the demographic balance between Indigenous, Spanish, and mixed-race populations that the later casta system tried to classify.
How we know: Tree-ring records reconstructing the 16th-century megadrought, combined with epidemiological reanalysis of contemporary Spanish accounts of symptoms (which do not match smallpox but do match hemorrhagic fever), let researchers separate the 1545 and 1576 cocoliztli outbreaks from the earlier, confirmed 1520 smallpox epidemic; the death toll is treated as an estimate because no census exists from the period, and different scholars have offered different ranges.
1519-1520 smallpox epidemic: Killed an estimated half of central Mexico's population · 1545-1548 cocoliztli epidemic: 5-15 million dead, up to 80% of survivors · 1576-1578 cocoliztli epidemic: 2-2.5 million dead, about 50% of remaining population · Population, 1519 vs. 1600: 15-30 million vs. approximately 2 million
- 1565-1815Well documented
Reputable source · 2 sourceswhy?
Best source: Manila Galleon
The domain "worldhistory.org" is on our Reputable source registry.The Manila Galleon Trade Links Mexico to Asia
Beginning in 1565, Spanish treasure ships called Manila galleons sailed annually between Acapulco, Mexico, and Manila in the Philippines, carrying perhaps 50 tons of silver a year, and at times up to 3 million silver pesos per voyage, westward across the Pacific. In exchange, galleons returned to Mexico loaded with Chinese silk, porcelain, Persian carpets, spices, and other Asian goods; a roll of silk worth a fixed price in Manila could sell for ten times as much in the Americas, and merchants routinely made 150 to 200% profit on the round trip. The trade dominated Manila's economy for the better part of two centuries and continued until the final Manila galleon, the San Fernando, completed its voyage to Acapulco in 1815.
Why it matters: The galleon route made Mexican silver the world's first genuinely global currency and connected central Mexico's mining economy directly to Ming and Qing China's demand for silver, tying a Mexican port to a trade network spanning three continents two and a half centuries before anyone used the phrase global economy.
How we know: Spanish colonial shipping records and captured-cargo manifests document silver tonnage and peso counts per voyage; the 1815 final voyage is recorded in Spanish colonial administrative archives.
Route: Acapulco, Mexico to Manila, Philippines · Operated: 1565-1815 · Silver per voyage (peak): Up to 3 million silver pesos · Final voyage: The San Fernando, 1815
Sources - c. 1700s-1821Well documented
General source · 2 sourceswhy?
Best source: New to the Ackland: A Spanish Colonial Casta Painting by Ignacio de Castro
Cited as a "reference" source (no stronger domain match).Casta Paintings Chart Colonial Mexico's Racial Hierarchy
Beginning in the early 18th century, painters in New Spain produced casta paintings: sets, typically of sixteen scenes, depicting a man, woman, and child from different racial backgrounds, each labeled with the specific mixed-race category the child represented, such as mestizo for the offspring of a Spaniard and an Indigenous person. The genre reflected the era's Enlightenment interest in scientific classification, applied to a colonial society where a large share of the population was by then of mixed Spanish, Indigenous, and African descent. Little is known about who commissioned these paintings, though they were likely made largely for a European audience, quite possibly Spaniards returning home, who wanted a visual record of the racial composition of Spain's American colonies. Production of the genre ended after Mexican independence in 1821, when the new nation abolished official caste designations.
Why it matters: Casta paintings are now read less as a factual record of colonial life than as evidence of how colonial elites wanted their racial hierarchy imagined: a fixed, orderly ladder from Spaniard down through mixture, even though the society they depicted was in practice far more fluid than any sixteen-panel set could show. They remain the most direct visual evidence of how the casta system organized status, rights, and opportunity in New Spain.
How we know: Surviving casta paintings in museum collections carry their original racial-category labels, letting historians read the classification system directly from period artwork rather than inferring it only from legal or tax records.
Genre period: Early 1700s to 1821 · Typical format: Sets of 16 panels, one racial mixture per panel · Notable painter: Miguel Cabrera (1763 set) · Genre ended: 1821, with Mexican independence
- 1765-1771Well documented
Peer-reviewed · 2 sourceswhy?
Best source: Bourbon Reforms and State Capacity in the Spanish Empire
Cited as a "journal" source (no stronger domain match).The Bourbon Reforms Tighten Spanish Control Over New Spain
Spain's Bourbon monarchs, starting with Charles III, pushed through sweeping changes meant to modernize and centralize the empire and increase crown revenue, most intensely in the second half of the 18th century. Jose de Galvez spent six years, from 1765 to 1771, as visitor general of public finance in New Spain, overhauling revenue collection, strengthening crown monopolies including tobacco, and reorganizing tax collection so thoroughly that his powers as royal inspector could not be overruled even by the sitting viceroy. Later reforms in the 1780s created intendancies, new administrative districts run by crown-appointed officials answering directly to Spain, while trade decrees in 1778 loosened some restrictions on intercolonial shipping.
Why it matters: The Bourbon Reforms increased royal revenue and control but did so by sidelining American-born Spaniards (creoles) in favor of officials sent from Spain, deepening the resentment that would help fuel the independence movement a generation later. Galvez's centralizing model, extended empire-wide after he became Minister of the Indies in 1776, reshaped Spanish colonial administration from Argentina to Texas.
How we know: Spanish crown records document Galvez's appointment, his specific reforms during the 1765-1771 visita general, and his subsequent promotion to Minister of the Indies in 1776.
Galvez's visita general: 1765-1771, New Spain · Key reforms: Tax overhaul, tobacco monopoly, intendancy system (1780s) · Free Trade Decrees: 1778 · Galvez becomes Minister of the Indies: 1776
- 16 September 1810Well documented
Primary source · 2 sourceswhy?
Best source: Father Miguel Hidalgo y Costilla
The domain "loc.gov" is on our Primary source registry.Hidalgo Rings the Bell at Dolores and Launches the War of Independence
Miguel Hidalgo y Costilla, the criollo priest of the parish of Dolores, learned in the early hours of 16 September 1810 that Spanish authorities had discovered the anti-royalist conspiracy he had joined with Ignacio Allende and others. Rather than wait for arrest, he rang the church bells as if calling parishioners to Mass and instead urged the largely Indigenous and mestizo crowd to revolt, an act remembered as the Grito de Dolores. The exact wording is not preserved, but accounts agree he invoked the Virgin of Guadalupe and denounced 'bad government' and the gachupines, Spanish-born colonists. Hidalgo's improvised army, reported at around 60,000, took the silver city of Guanajuato but suffered defeats at Aculco and elsewhere, and by November had failed to take Mexico City. Hidalgo was captured in Coahuila on 21 March 1811 and executed after being stripped of his priesthood.
Why it matters: Hidalgo's revolt failed militarily within a year, but it set in motion an eleven-year war that eventually did win independence, and its call for the end of Spanish rule, land redistribution, and racial equality shaped the demands of every insurgent leader who followed him, including Jose Maria Morelos. September 16 is now celebrated as Mexico's Independence Day.
How we know: Manuscript records held in the Library of Congress's Peter Force Collection document Hidalgo's biography and the Inquisition's earlier case against him; period accounts from multiple independent chroniclers describe the 16 September uprising and its immediate military campaign.
Location: Dolores, Guanajuato · Date: 16 September 1810 · Reported force size: c. 60,000 · Hidalgo captured and executed: 21 March 1811 (captured)
- 22 October 1814Well documented
Primary source · 2 sourceswhy?
Best source: Jose Maria Morelos y Pavon (1765-1815) and Constitution of Apatzingan
The domain "loc.gov" is on our Primary source registry.Morelos Convenes the Congress of Chilpancingo and Abolishes Slavery
Jose Maria Morelos, a priest Hidalgo had dispatched to organize the insurgency in southern Mexico, abolished slavery and the racial caste hierarchy in the territory he controlled, took Chilpancingo and much of the south by 1811, and captured the port of Acapulco in April 1813. He convened the Congress of Chilpancingo in September 1813, which produced the Constitution of Apatzingan, promulgated on 22 October 1814, Mexico's first constitution. It accepted Catholicism, popular sovereignty, and civil rights across its 242 articles, and established a tripartite government, though it was never implemented because Morelos's forces collapsed under royalist pressure. Captured on 5 November 1815, Morelos was stripped of his priestly status and executed by firing squad on 22 December 1815.
Why it matters: The Constitution of Apatzingan never took effect, but it set out for the first time in writing what an independent Mexican state should look like, and Morelos's abolition of slavery and caste distinctions pushed the independence movement's social program further than Hidalgo had, a program later insurgents like Vicente Guerrero carried forward.
How we know: The published 1821 edition of the Constitution of Apatzingan survives in the Library of Congress Law Library's rare books collection, and Morelos's military campaign and capture are documented in Spanish colonial military records.
Congress of Chilpancingo: Convened September 1813 · Constitution of Apatzingan: Promulgated 22 October 1814 · Articles: 242 · Morelos executed: 22 December 1815
- 27 September 1821Well documented
Primary source · 2 sourceswhy?
Best source: Mexico's Plan of Iguala, 1821
Cited as a "primary" source (no stronger domain match).The Plan of Iguala and the Treaty of Cordoba Win Independence
On 24 February 1821, royalist officer Agustin de Iturbide and insurgent leader Vicente Guerrero jointly proclaimed the Plan of Iguala, promising three guarantees: Roman Catholicism as the sole religion, full independence from Spain, and equal rights for Spanish- and American-born residents alike, backed by a new Army of the Three Guarantees. Article 11 of the plan explicitly abolished caste distinctions, declaring all inhabitants equal citizens. Spain's representative in Mexico, Juan O'Donoju, signed the Treaty of Cordoba on 24 August 1821, ratifying the plan and Mexican independence, and the Army of the Three Guarantees entered Mexico City on 27 September 1821, with independence formally declared the next day.
Why it matters: Independence came not from Hidalgo's or Morelos's popular insurgencies, both defeated years earlier, but from a compromise between conservative royalists and the surviving insurgent leadership, which is why the settlement kept a monarchy and the Church's privileged position rather than the more radical social program Morelos had fought for. That compromise's fragility showed within two years, when Iturbide's short-lived empire collapsed.
How we know: The Plan of Iguala and the Treaty of Cordoba both survive as documents in Spanish and Mexican archives, including the Library of Congress Law Library's copy of the Plan of Iguala.
Plan of Iguala proclaimed: 24 February 1821 · Treaty of Cordoba signed: 24 August 1821 · Army enters Mexico City: 27 September 1821 · Key figures: Agustin de Iturbide, Vicente Guerrero, Juan O'Donoju
- 21 April 1836Well documented
Primary source · 2 sourceswhy?
Best source: Antonio Lopez de Santa Anna (1794-1876)
The domain "loc.gov" is on our Primary source registry.Santa Anna Loses Texas and Rises Again on One Leg
Antonio Lopez de Santa Anna, who had joined the independence cause under the Plan of Iguala in 1821, led Mexican forces against Texian rebels in 1836, winning the Battle of the Alamo on 6 March but suffering a catastrophic defeat at San Jacinto on 21 April, where Sam Houston's army routed his forces in eighteen minutes. Santa Anna was captured and, to save his life, signed the Treaties of Velasco recognizing Texan independence, an agreement the Mexican government refused to honor. He returned to public life after losing a leg fighting a French invasion at Tampico in 1838, becoming a national hero once more, and went on to serve as president on separate occasions between 1833 and 1855, described by contemporaries as Mexico's quintessential caudillo, a strongman who moved between liberal and conservative politics as his fortunes required.
Why it matters: Santa Anna's repeated returns to power, despite presiding over Texas's loss in 1836 and Mexico's defeat in the war with the United States a decade later, illustrate how unstable early republican Mexico's politics were: no single defeat, however severe, permanently ended a caudillo's career if he retained a regional power base like Santa Anna's in Veracruz.
How we know: Mexican and Texan military records document the Alamo, San Jacinto, and the Treaties of Velasco; Santa Anna's subsequent presidencies are documented in Mexican government records through his final exile in 1855.
Battle of San Jacinto: 21 April 1836, lasted c. 18 minutes · Santa Anna's presidencies: Multiple terms, 1833-1855 · Lost leg: Battle of Tampico, 1838, against French forces · Final exile: 1855
- 2 February 1848Well documented
Primary source · 2 sourceswhy?
Best source: Treaty of Guadalupe Hidalgo (1848)
Cited as a "primary" source (no stronger domain match).The Mexican-American War Ends With the Loss of Half the National Territory
A boundary dispute over whether Texas's border with Mexico lay at the Rio Grande or the Nueces River, combined with U.S. president James Polk's expansionist ambitions, led the United States to declare war on Mexico on 13 May 1846 after skirmishes in the disputed territory. Nearly two years of fighting ended when the Treaty of Guadalupe Hidalgo was signed on 2 February 1848 at the city of that name, to which the Mexican government had fled as U.S. forces advanced. Under its terms, Mexico ceded about 55% of its territory, including present-day California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas, and Wyoming, and relinquished all claims to Texas, recognizing the Rio Grande as the border. The United States paid Mexico $15 million and agreed to settle its own citizens' debt claims against the Mexican government; the U.S. Senate ratified the treaty 34 to 14 on 10 March 1848, but deleted the article guaranteeing protection of existing Mexican land grants.
Why it matters: The treaty is the single largest territorial loss in Mexico's history, cutting the nation to less than half the size it had been at independence in 1821, and the Senate's removal of the land-grant protections left many Mexican landowners in the ceded territory without secure title under the new U.S. jurisdiction, a grievance that outlived the war by generations.
How we know: The treaty text survives in full at the U.S. National Archives, and the Senate's ratification vote and its amendment removing Article X are recorded in the congressional record.
War declared: 13 May 1846 · Treaty signed: 2 February 1848, Guadalupe Hidalgo · Territory ceded: c. 55% of Mexico's national territory · U.S. payment: $15,000,000
- 5 February 1857Well documented
Primary source · 2 sourceswhy?
Best source: Benito Juarez (1806-1872)
The domain "loc.gov" is on our Primary source registry.Juarez and La Reforma Separate Church and State
Benito Juarez, born in a Zapotec-speaking village in Oaxaca and orphaned before age four, rose through law and Oaxaca's governorship to become a leading liberal reformer. As Minister of Justice, he authored the Ley Juarez of 1855, ending separate military and Church courts, and as Minister of Government helped push through the Ley Lerdo of 1856, forcing the Church to sell land not used directly for worship. These reforms culminated in the Constitution of 1857, sworn in on 5 February 1857, which enshrined freedom of religion, speech, and the press alongside the church-state separation. The Church's demand that anyone swearing loyalty to the new constitution be excommunicated, met by the government's insistence that all officials take that oath, triggered the Reform War (Guerra de Reforma) of 1858 to 1861 between liberals under Juarez and conservatives defending clerical privilege. During the war Juarez, as president of the Supreme Court and thus next in line for the presidency after a conservative coup deposed his predecessor, issued further decrees in 1859 confiscating uncompensated Church property, establishing civil marriage, and formally separating church and state; the liberals won the war by the end of 1860.
Why it matters: La Reforma remade Mexico's legal relationship between religion and government in ways that still define the country's secular constitutional order, but the fight to enforce those changes plunged Mexico into a three-year civil war and left the treasury so depleted that Juarez's decision to suspend foreign debt payments in 1861 gave France the pretext for the invasion that followed within a year.
How we know: The Constitution of 1857 survives in full in the Library of Congress Law Library's rare book collection, and Juarez's biography and the sequence of reform decrees are documented in the Library of Congress's dedicated exhibition on this period of Mexican history.
Ley Juarez: 23 November 1855 · Ley Lerdo: 25 June 1856 · Constitution of 1857: Sworn in 5 February 1857 · Reform War: 1858-1861
Sources- The Mexican Revolution and the United States exhibit, Library of Congress. Benito Juarez (1806-1872) · website
- The Mexican Revolution and the United States exhibit, Library of Congress. Federal Constitution of the United States of Mexico, Sanctioned and Sworn in by the General Constitutional Congress (February 5, 1857) · website
- 5 May 1862Well documented
Primary source · 2 sourceswhy?
Best source: Porfirio Diaz in 1867 (age 37)
The domain "loc.gov" is on our Primary source registry.France Invades Mexico and Installs Maximilian as Emperor
After Juarez suspended payments on Mexico's foreign debt in 1861, Britain, Spain, and France signed a tripartite agreement to intervene and recover the money, but Napoleon III alone pursued a larger goal: reviving French global influence by installing a monarchy in Mexico. A French army advancing on Puebla was unexpectedly defeated on 5 May 1862, a battle in which a young general named Porfirio Diaz played a decisive role, but France sent reinforcements, took Mexico City by 1863, and in 1863 Napoleon III invited Austrian archduke Maximilian von Habsburg to become Emperor of Mexico; Maximilian accepted and arrived in 1864 with French backing and the support of Mexican conservatives and the Church. Juarez's government retreated but never surrendered, and Diaz continued fighting the French as a guerrilla commander even after being captured on several occasions, escaping each time, until he took Oaxaca on 31 October 1866 and helped defeat French forces again at Puebla on 2 April 1867.
Why it matters: Cinco de Mayo commemorates a battle Mexico won but a war it initially lost, since the French occupation succeeded in installing Maximilian for three years; the date's later prominence, especially in the United States, has more to do with 19th-century Mexican-American communities adopting it than with the battle's immediate strategic effect, which was to delay rather than prevent the French intervention.
How we know: The Office of the Historian's account of the French intervention documents the 1861 tripartite agreement, Napoleon III's aims, and Maximilian's 1863-1864 installation; Diaz's role at both battles of Puebla is recorded in the Library of Congress's exhibition materials on his career.
Battle of Puebla (Cinco de Mayo): 5 May 1862 · Maximilian invited / arrived: 1863 / 1864 · Diaz retakes Oaxaca: 31 October 1866 · Second Battle of Puebla: 2 April 1867
- 19 June 1867Well documented
Primary source · 2 sourceswhy?
Best source: Benito Juarez (1806-1872)
The domain "loc.gov" is on our Primary source registry.Maximilian Is Executed at Queretaro
With the American Civil War over by 1865, the United States began actively supporting Juarez's Republican forces, and under pressure from a reasserted Monroe Doctrine, Napoleon III withdrew French troops from Mexico beginning in 1866. Abandoned by the government that had crowned him, Maximilian was captured at Queretaro and, alongside his generals Miguel Miramon and Tomas Mejia, executed by a Republican firing squad at the Cerro de las Campanas at 6:40 a.m. on 19 June 1867. Victor Hugo, Giuseppe Garibaldi, and multiple European monarchs petitioned Juarez to spare Maximilian's life; Juarez refused, judging that clemency would undercut the message that Mexico would not tolerate further foreign intervention after a war that had already cost many Mexican lives. News of the execution reached Paris on 1 July 1867, just as Napoleon III was opening that year's Universal Exposition, and the French painter Edouard Manet completed a series of four paintings and a lithograph on the subject within about eighteen months.
Why it matters: Maximilian's execution ended the Second Mexican Empire and the last serious European attempt to install a monarchy in the Americas by force, and it restored Juarez to a presidency he would hold until his death in 1872. The event also became one of the 19th century's most-depicted political executions in European art, cementing its symbolic weight as a verdict against foreign intervention.
How we know: The Museum of Modern Art's research on Manet's paintings documents the execution date and the diplomatic pleas for clemency; Juarez's reasoning for refusing clemency is recorded in period accounts of his decision-making during the trial.
Location: Cerro de las Campanas, Queretaro · Date: 19 June 1867 · Also executed: Generals Miguel Miramon and Tomas Mejia · Juarez restored to presidency: 1867 (reelected December, and again 1871)
- 23 November 1876Well documented
Primary source · 2 sourceswhy?
Best source: President Porfirio Diaz at Age 80
The domain "loc.gov" is on our Primary source registry.Diaz Seizes Power and Begins the Porfiriato
Porfirio Diaz, born in Oaxaca in 1830 and a decorated general from the war against the French intervention, launched an unsuccessful revolt against Juarez's reelection in 1871 and, after Juarez's death and the presidency of Sebastian Lerdo de Tejada, launched a second revolt under the Plan of Tuxtepec in January 1876, calling for no reelection. This one succeeded, and Diaz became president on 23 November 1876. Aside from one four-year term (1880-1884) when an ally, Manuel Gonzalez, held the office while Diaz served in his cabinet and as governor of Oaxaca, Diaz held the presidency continuously from 1884 until 1911, using electoral fraud, a rural police force called the Rurales, and periodic repression of critics to stay in power despite having run on an anti-reelection platform.
Why it matters: The Porfiriato's economic modernization, discussed in the following event, came paired with the very political stagnation Diaz had once campaigned against, a contradiction his own advisers, the cientificos, defended as necessary for stability but which built the resentment that exploded in the 1910 revolution.
How we know: Diaz's military and political career, from the Revolt of La Noria in 1871 through the successful Plan of Tuxtepec, is documented in the Library of Congress's exhibition on Mexico under Diaz, drawing on period photographs and government records.
Born: Oaxaca City, 1830 · Took power: 23 November 1876 (Plan of Tuxtepec) · Years in office: 1876-1880, 1884-1911 · Resigned: 25 May 1911
- c. 1880-1910Well documented
Primary source · 2 sourceswhy?
Best source: Railroads in Mexico (1884-1885) / The Consequences of Progress
The domain "loc.gov" is on our Primary source registry.Railroads and Foreign Capital Modernize the Porfiriato, and Inequality Deepens
Under Diaz, Mexico's rail network grew to 10,000 miles of track by 1910, connecting Mexico City to major ports and opening the interior to commercial agriculture and foreign investment in mines and factories. International capital financed haciendas that restructured agricultural land for export markets, and cities grew as new industry drew rural workers off the land, while a quarter of Mexicans became literate even though Diaz opened few new public schools. But the benefits concentrated among elites and foreign investors, and the arrival of large haciendas and corporations pushed many mestizo and Indigenous farmers into wage labor or debt peonage on land their communities had worked for generations, while the government's Rurales police force and federal troops enforced order in the countryside.
Why it matters: The Porfiriato is the clearest case in Mexican history of economic modernization achieved by transferring land and political power away from ordinary Mexicans toward a landed and foreign-invested elite, and the resulting rural dispossession is precisely the grievance that Emiliano Zapata's movement in Morelos would organize against within a few years of Diaz's fall.
How we know: Railroad mileage and industrial figures are documented in Library of Congress exhibition materials drawing on period government and business records; the connection between hacienda expansion and rural dispossession is corroborated by the biographies of revolutionary leaders like Zapata who organized specifically around land seizures during this period.
Rail network by 1910: 10,000 miles · Literacy gain: About one quarter of Mexicans became literate · Rural enforcement: Rurales police force plus federal troops · Presidency: 1876-1880, 1884-1911
- 20 November 1910Well documented
Primary source · 2 sourceswhy?
Best source: The Creelman Interview / President Porfirio Diaz at Age 80
The domain "loc.gov" is on our Primary source registry.Madero Challenges Diaz and Sparks the Mexican Revolution
In March 1908, Diaz told American journalist James Creelman that Mexico was ready for democracy and that he might not seek reelection in 1910, remarks meant for a foreign audience but soon translated and published inside Mexico, where they encouraged Francisco Madero and other reformers to organize openly. When Diaz reversed course and ran again in 1910, having Madero jailed during the campaign, Madero called for revolt from exile in the United States, and fighting broke out on 20 November 1910. Diaz's forces lost ground steadily over the following months, and after guerrilla resistance in the south and battlefield defeats in the north, Diaz's representatives signed the Treaty of Ciudad Juarez with Madero on 21 May 1911; Diaz resigned four days later, on 25 May, and left for exile in Paris, where he died in 1915.
Why it matters: The 1910 revolt is the formal start of the Mexican Revolution, a decade of civil war that killed an estimated one to two million people and ended with an entirely new constitutional order in 1917. Madero's own limited ambitions, restoring democratic elections rather than redistributing land, quickly put him at odds with more radical allies like Zapata, setting up the movement's next phase.
How we know: The Creelman interview survives in its original March 1908 Pearson's Magazine publication, held at the Library of Congress, and the Treaty of Ciudad Juarez and Diaz's resignation date are documented in Mexican government records from May 1911.
Creelman interview: March 1908, Pearson's Magazine · Madero's revolt begins: 20 November 1910 · Treaty of Ciudad Juarez: 21 May 1911 · Diaz resigns: 25 May 1911
- 28 November 1911Well documented
Primary source · 2 sourceswhy?
Best source: Emiliano Zapata (1879-1919) / Zapata's Platform Rallies Indigenous Support
The domain "loc.gov" is on our Primary source registry.Zapata Issues the Plan of Ayala and the Cry of 'Tierra y Libertad'
Emiliano Zapata, a farmer and horseman from Anenecuilco, Morelos, elected president of his village council in 1909, had already spent years fighting hacienda encroachment on communal land before Madero's revolt against Diaz began. After Madero took the presidency but showed little interest in immediate land reform, Zapata refused to disarm his forces and, with schoolteacher Otilio Montano, wrote the Plan of Ayala on 28 November 1911, the revolution's most radical document, demanding the return of land stolen by haciendas and confiscation without compensation of estates that refused to comply. The plan's rallying cry, eventually shortened after Zapata's death to 'Tierra y Libertad' (Land and Liberty), drew Nahua, Maya, and Zapotec communities across central and southern Mexico into his movement. By 1914 Zapata's forces controlled Morelos and threatened Mexico City itself, and he allied briefly with Pancho Villa before returning home to pursue land reform directly; he was ambushed and assassinated on 10 April 1919.
Why it matters: Zapata's insistence on land reform as the revolution's non-negotiable core, rather than merely political change, forced every subsequent revolutionary faction to reckon with agrarian demands, and Article 27 of the 1917 Constitution, mandating the return of illegally seized peasant land, is a direct legacy of the fight he refused to abandon even when it meant breaking with the president his own revolt had helped install.
How we know: The Plan of Ayala survives as a written document from November 1911; Zapata's biography, land seizures, and eventual assassination are documented across period photographs and records held in the Library of Congress's collection on the Mexican Revolution.
Plan of Ayala issued: 28 November 1911 · Co-author: Otilio Montano · Slogan: Tierra y Libertad (Land and Liberty) · Assassinated: 10 April 1919
- c. 1913-1915Well documented
Primary source · 2 sourceswhy?
Best source: Francisco 'Pancho' Villa Before the Revolution
The domain "loc.gov" is on our Primary source registry.Pancho Villa Turns Porfirian Injustice Into a Revolutionary Army
Jose Doroteo Arango Arambula, born in Durango in 1878 and known to history as Francisco 'Pancho' Villa, grew up a sharecropper under the Porfiriato and, after shooting a hacienda official who tried to kidnap his teenage sister in 1894, escaped a firing squad, fled to Chihuahua, and adopted the name Pancho Villa. Working for years for American ranchers and miners, he built a meat business that regional strongman Luis Terrazas moved to shut down through new land laws, pushing Villa into full-time banditry and eventually the revolution. Villa fought first against Diaz and then against Huerta after Huerta seized power in a coup, commanding forces that made him one of the revolution's most effective military leaders; he allied briefly with Zapata in 1914, and the two met in Mexico City that December, but the alliance collapsed the following year after Villa lost a major battle to Alvaro Obregon, Carranza's general. Villa surrendered during Adolfo de la Huerta's interim presidency in 1920, receiving a ranch and a guard of fifty men, before being assassinated in 1923.
Why it matters: Villa's rise from dispossessed sharecropper to army commander embodies how the Porfiriato's economic order, which benefited large landowners and foreign investors while leaving ordinary rural Mexicans with shrinking legal protection, directly produced the armed movements that overthrew it. His Division of the North was decisive in the fighting against both Diaz and Huerta before the revolutionary coalition itself fractured.
How we know: Villa's early life, the 1894 shooting, his flight to Chihuahua, and his subsequent military career are documented in Library of Congress exhibition materials and contemporary newspaper coverage of the revolution.
Born: Durango, 5 June 1878 · Fled to Chihuahua: 1902 · Allied with Zapata: 1914 · Assassinated: 1923
- 5 February 1917Well documented
Primary source · 2 sourceswhy?
Best source: The Constitution of 1917
Cited as a "primary" source (no stronger domain match).The Constitution of 1917 Codifies the Revolution's Demands
By late 1916, Venustiano Carranza controlled every Mexican state except Chihuahua and Morelos and convened a Constitutional Convention in Santiago de Queretaro that November, drawing mostly young, university-educated delegates who proved considerably more radical on social policy than Carranza expected. The resulting Constitution of 1917, ratified on 5 February 1917 and still in force today, runs to 137 articles. Article 3 established free, secular, compulsory public education outside clerical control; Article 27 mandated the return of land seized from peasant communities during the Porfiriato, even without written titles, and allowed government expropriation of land not put to appropriate use; and Article 123 set an eight-hour workday, a six-day week, a minimum wage, and the right of workers to organize and strike.
Why it matters: The 1917 Constitution is generally treated as the point at which the Mexican Revolution's demands became law rather than only battlefield slogans, and its labor and land provisions influenced other 20th-century constitutions that followed. Its core articles on education, land, and labor remained the legal foundation of Mexican governance for the rest of the century.
How we know: The Constitution's full text was printed in the Diario Oficial on 5 February 1917 and survives in the Library of Congress Law Library's collection, including the specific articles on education, land, and labor cited above.
Convention convened: November 1916, Santiago de Queretaro · Ratified: 5 February 1917 · Total articles: 137 · Key articles: 3 (education), 27 (land), 123 (labor)
- 4 March 1929Well documented
Primary source · 3 sourceswhy?
Best source: Obregon's Reelection and Assassination
The domain "loc.gov" is on our Primary source registry.The PNR Forms and Begins Seven Decades of One-Party Rule
President-elect Alvaro Obregon, who had governed Mexico from 1920 to 1924 and won reelection in 1928 after Congress redefined the no-reelection rule to permit non-consecutive terms, was shot five times in the head by Jose de Leon Toral, a member of the Cristero movement opposed to the constitution's anti-clerical laws, on 17 July 1928, less than two weeks after his victory. The assassination threatened to fracture Mexico's revolutionary leadership into competing armed factions again, so former president Plutarco Elias Calles organized the Partido Nacional Revolucionario, founded on 4 March 1929 to unify the surviving leaders and combatants of the revolution under one political organization and guarantee peaceful transfers of power. The party was renamed the Partido de la Revolucion Mexicana in 1938 and, in 1946, the Institutional Revolutionary Party (PRI), the name it held through 71 consecutive years of rule until 2000.
Why it matters: The PNR's founding purpose, ending the pattern of assassination and armed rebellion that had killed Obregon and threatened to repeat itself, succeeded: Mexico avoided further civil war for the rest of the century, but at the cost of building a single-party system that would dominate Mexican politics without serious electoral challenge for seven decades.
How we know: The party's founding date, its organizing committee under Calles, and its later renamings are documented in Mexican institutional and academic historical sources; Obregon's assassination is independently documented in period U.S. and Mexican records held at the Library of Congress.
Obregon assassinated: 17 July 1928 · PNR founded: 4 March 1929, by Plutarco Elias Calles · Renamed PRM: 1938 · Renamed PRI: 1946
Sources- The Mexican Revolution and the United States exhibit, Library of Congress. Obregon's Reelection and Assassination · website
- Estudios de Historia Moderna y Contemporanea de Mexico, SciELO Mexico. Partido Nacional Revolucionario (PNR): Metodo y practica en la seleccion de candidatos a puestos de eleccion popular (1929-1938) · journal
- Library of Congress Country Studies. Mexico - The Maximato · reference
- 18 March 1938Well documented
Reputable source · 2 sourceswhy?
Best source: Mexican Expropriation of Foreign Oil, 1938
The domain "history.state.gov" is on our Reputable source registry.Cardenas Nationalizes the Oil Industry
After foreign oil companies, which controlled the large majority of Mexico's petroleum production (Royal Dutch/Shell's Mexican Eagle Company alone accounted for over 60%, with U.S. firms Jersey Standard and Standard Oil of California around 30% combined), rejected a government labor commission's proposed wage agreement and challenged it all the way to the Mexican Supreme Court, President Lazaro Cardenas signed an order on 18 March 1938 expropriating nearly all foreign oil company assets in the country. He created Petroleos Mexicanos (PEMEX) that June to hold a state monopoly over the industry and barred foreign oil companies from operating in Mexico. The move proved immensely popular domestically, and March 18 became an unofficial national holiday. The U.S. government, while backing American firms' right to seek compensation, also affirmed Mexico's right to expropriate foreign assets provided compensation followed, and the two countries settled the dispute through the Cooke-Zevada agreement on 18 April 1942, under which Mexico paid roughly $29 million to the affected American companies.
Why it matters: The 1938 expropriation, grounded in Article 27 of the 1917 Constitution asserting national ownership of the subsoil, remains one of the Mexican Revolution's most concrete and lasting legacies: it created a state oil monopoly that endured for over 75 years and turned the date into a symbol of Mexican economic sovereignty against foreign capital.
How we know: The Office of the Historian's account of the expropriation documents the companies involved, the date of Cardenas's order, and the terms of the eventual 1942 settlement between the U.S. and Mexican governments.
Expropriation order: 18 March 1938 · PEMEX established: 7 June 1938 · Companies affected: 17 foreign oil firms · Cooke-Zevada settlement: 18 April 1942, c. $29 million
- 1958-1970Well documented
Peer-reviewed · 2 sourceswhy?
Best source: Catch-up Growth Followed by Stagnation: Mexico, 1950-2010
Cited as a "journal" source (no stronger domain match).The Mexican Miracle Delivers Two Decades of Rapid Growth
Mexico's economic policy in the years generally dated from 1958 to 1970, under presidents Adolfo Lopez Mateos and Gustavo Diaz Ordaz and often called Desarrollo Estabilizador (Stabilizing Development) or the Mexican Miracle, pursued import substitution industrialization: building domestic industries to replace imported goods behind tariff walls, financed partly through the state development bank Nacional Financiera. The government kept the peso fixed at 12.5 to the dollar and held average annual inflation to 3.8%, while real economic output grew at an average annual rate of 6.7% and manufacturing growth averaged 9.0% across both administrations. A stated second objective of the period, alongside growth, was reducing income inequality, though the strategy's benefits concentrated heavily in urban industrial sectors and among the growing middle class.
Why it matters: The Mexican Miracle is the reference point against which every subsequent Mexican economic period, including the 1980s debt crisis and the shift toward trade liberalization, has been measured, and it demonstrates that the political stability the PRI's one-party system provided, whatever its democratic costs, did coincide with a genuinely unusual quarter-century of macroeconomic growth and price stability.
How we know: Growth, inflation, and exchange-rate figures for the period are documented in peer-reviewed economic history research; the classification of the era as running from 1958 to 1970 draws on economist Leopoldo Solis's periodization, cited in that same scholarly literature.
Period: 1958-1970 (Desarrollo Estabilizador) · Average real growth: 6.7% per year · Average inflation: 3.8% per year · Exchange rate: Fixed at 12.5 pesos per US dollar
- 2 October 1968Debated
Reputable source · 2 sourceswhy?
Best source: Tlatelolco Massacre, 1968
The domain "nsarchive.gwu.edu" is on our Reputable source registry.Government Forces Kill Student Protesters at Tlatelolco
On the evening of 2 October 1968, roughly 10,000 university and high school students gathered in Mexico City's Plaza de las Tres Culturas at Tlatelolco to protest government repression of the student movement, ten days before the city was to host the Summer Olympics. Army, police, and unidentified armed men surrounded the square and opened fire with armored vehicles and heavy weapons; the Mexican government's official account claimed protesters shot first, a version documents made public since 2000 suggest was staged by the government itself. The National Security Archive at George Washington University spent eight months researching Mexican national archives and documented deaths of 44 people, 34 identified by name and 10 unidentified, though a contemporary CIA report cited 24 civilian deaths and 137 wounded, and eyewitness and later estimates have ranged much higher, into the hundreds. In 2024, President Claudia Sheinbaum, whose mother had been dismissed from a university teaching post for denouncing the massacre, issued an official government apology for it.
Why it matters: Tlatelolco remains the starkest example of PRI-era state violence against political dissent, and the persistent uncertainty over the actual death toll, ranging across declassified sources from two dozen to several hundred, reflects a decades-long government effort to suppress the true scale of the killing rather than any genuine ambiguity about whether it happened.
How we know: The National Security Archive's declassified U.S. government documents, obtained through Freedom of Information Act requests and archival research inside Mexico, provide the most systematic documentation available, though the archive itself notes its sources, press accounts, intelligence officers, and Mexican officials, produced conflicting figures because no independent eyewitness accounting was possible at the time.
Location: Plaza de las Tres Culturas, Tlatelolco, Mexico City · Date: 2 October 1968 · Documented deaths (NSArchive): 44 (34 named, 10 unidentified) · Government apology: 2024, President Claudia Sheinbaum
- 2 July 2000Well documented
General source · 2 sourceswhy?
Best source: Mexico's Presidential, Legislative, and Local Elections of July 2, 2000
Cited as a "reference" source (no stronger domain match).Fox's Election Ends 71 Years of PRI Rule
On 2 July 2000, Vicente Fox of the National Action Party (PAN), running as part of the Alliance for Change coalition, won Mexico's presidential election with 42.52% of the vote against 36.10% for the PRI's Francisco Labastida and 16.64% for Cuauhtemoc Cardenas of the PRD, carrying 20 of Mexico's 32 states to Labastida's 11. Independent Mexican electoral authorities supervised the vote, and both defeated candidates conceded the same evening. It marked the first time an opposition candidate had won the Mexican presidency in 71 years, since the PNR's founding in 1929, ending the longest continuous single-party rule in the world at that time. Fox took office on 1 December 2000, but neither his coalition nor any single party held a majority in either chamber of Congress.
Why it matters: Mexico's ability to end 71 years of single-party rule through a peaceful, internationally credible election, rather than through revolution or coup, the two methods that had ended every previous era of Mexican governance, marked the country's definitive transition to competitive multi-party democracy.
How we know: Official vote totals and the state-by-state breakdown are recorded in a Congressional Research Service report prepared for the U.S. Congress immediately after the election.
Election date: 2 July 2000 · Fox's vote share: 42.52% · States won (Fox vs. Labastida): 20 vs. 11 · Fox inaugurated: 1 December 2000
- December 2006Well documented
Unclassified source · 2 sourceswhy?
Best source: Mexico's Long War: Drugs, Crime, and the Cartels
Cited as a "website" source (no stronger domain match).Calderon Launches the War on Drug Cartels
President Felipe Calderon, who took office on 1 December 2006 after a closely contested election, declared war on Mexico's drug cartels within weeks of his inauguration, launching Operation Michoacan, an initial deployment of federal troops and police against organized crime in his home state before expanding the campaign nationally. Over his 2006-2012 term, Calderon deployed tens of thousands of military personnel, frequently replacing local police forces he considered corrupt, targeting cartels including the Sinaloa Cartel led by Joaquin 'El Chapo' Guzman. The government registered more than 120,000 homicides during Calderon's six years in office, roughly double the toll under his predecessor, and Mexico has recorded more than 463,000 homicides in total since the war began in 2006, with violence continuing to climb under subsequent administrations.
Why it matters: Calderon's militarized strategy did capture or kill numerous cartel leaders, but the resulting power vacuums repeatedly splintered organizations into smaller, more violent groups rather than reducing violence, a pattern that continued for years after his term ended and that reshaped how both the Mexican and U.S. governments approach organized crime along the border.
How we know: Homicide totals for Calderon's term and the cumulative post-2006 toll are documented by the Mexican government's own crime statistics, as reported and analyzed by the Council on Foreign Relations.
Calderon's term: 1 December 2006 - 30 November 2012 · Homicides under Calderon: Over 120,000 · Total homicides since 2006: Over 463,000 · Major cartel named: Sinaloa Cartel (Joaquin 'El Chapo' Guzman)