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1325-1400s CEReputable source · 2 sourcesWell documented

Chinampas and Causeways Turn a Swamp Into a Capital

Engineered floating gardens and raised roads make an unwanted marshy island livable, then dominant

On the timeline · around 1325-1400s CE · Subjects of the TepanecMigration and the Founding of TenochtitlanSubjects of the TepanecChinampas and Causeways Turn a Swamp Into a Capital1275130013251350

Quick facts

Structure
Artificial islands on posts, filled with lake mud and vegetation
Typical size
8-100 m long, 2-25 m wide
Causeways
Three, running north, east, and west, with removable bridges
Still in use
Xochimilco, Mexico City

What happened

The island the Mexica settled had almost no farmland, so they built it themselves using chinampas, artificial islands constructed by driving wooden posts into the shallow lakebed, weaving reed and branch fences called chinamitl between them, and filling the enclosures with mud dredged from the lake bottom and layered with vegetation. World History Encyclopedia describes chinampas ranging from 8 to 100 meters long and 2 to 25 meters wide, with willow trees planted at the corners so their roots would anchor the structure. The nutrient-rich lake water and canal mud made these plots extraordinarily productive, allowing multiple harvests a year of maize, beans, squash, and flowers. As the city grew, three causeways running north, east, and west connected the island to the mainland, built with removable wooden bridges over gaps so canoes could pass and so the causeways could be broken during an attack.

Why it matters

This engineering solved the problem that should have made Tenochtitlan impossible: a landless people building a capital on a lake with no farmland of its own. The food surplus from chinampa agriculture fed a city that reached an estimated 200,000 people, among the largest in the world at the time, and the causeways gave a lake-bound capital the overland connections an empire needed.

How we know

Chinampas are still farmed today in Xochimilco, on the southern edge of Mexico City, giving archaeologists and agronomists a living example of the technique alongside descriptions in the Florentine Codex, which depicts the willow trees used to stabilize the plots.

Sources

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Part of a timelineThe Aztec Empire25 events · From a wandering clan on a swampy island to the dominant power of Mesoamerica, and its end in a 93-day siegeView all →