The United States Bans the Importation of Enslaved People
The 1808 act closes the legal international trade to America on the earliest date the Constitution allowed, but leaves slavery and the domestic trade intact
Quick facts
- Effective date
- January 1, 1808
- Constitutional basis
- Article I, Section 9
- Prior step
- 1800 act banning US participation in foreign slave trade
- Left intact
- domestic slave trade between US states
What happened
Article I, Section 9 of the US Constitution barred Congress from prohibiting the importation of enslaved people before 1808, a compromise struck at the Constitutional Convention to secure Southern states' support. An 1800 act of Congress had already made it illegal for Americans to participate in the international slave trade between other countries and authorized US authorities to seize violating ships. Congress then passed the Act Prohibiting the Importation of Slaves, which took effect on January 1, 1808, the earliest date the Constitution permitted, making it illegal to bring enslaved people into any US port from a foreign country. The law imposed real penalties, including fines and imprisonment, on Americans who violated it. It did not, however, end slavery within the United States or prohibit the sale and transport of already-enslaved people between American states, a domestic trade that would grow substantially in the decades that followed.
Why it matters
The 1808 act closed off the legal supply of newly enslaved Africans to the United States, but because it left the domestic trade in already-enslaved people entirely legal, it shifted rather than ended the country's internal slave economy, feeding the massive forced migration historians call the second Middle Passage as cotton cultivation expanded into the Deep South.
How we know
The National Archives holds the original 1808 act and related customs manifests documenting the domestic coastwise trade that continued after the international trade was banned, and its education division has published a detailed lesson using these primary documents.
Sources
- National Archives. The Slave Trade · Primary source (author-declared)archives.gov · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- Gilder Lehrman Institute of American History. Historical Context: The Constitution and Slavery · Reputable sourcegilderlehrman.org · The domain "gilderlehrman.org" is on our Reputable source registry.
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Part of a timelineThe Atlantic Slave Trade29 events · Four centuries in which European traders forced an estimated 12.5 million Africans onto ships bound for the Americas, and the enslaved people, revolts, and abolitionists who fought it from the first crossing to the lastView all →