U.S. Bans International Slave Trade — Internal Trade and Illegal Imports Explode

The Act Prohibiting Importation of Slaves took effect January 1, 1808, the earliest date permitted by the Constitution. It made importing enslaved Africans a federal crime. Enforcement was minimal: the U.S. Navy's Africa Squadron was underfunded and the law carried no death penalty until 1820 (rarely enforced). Historians estimate 50,000–100,000 Africans were still illegally imported between 1808 and 1860. Meanwhile the ban supercharged the domestic slave trade: with no new African supply, enslaved people in the Upper South (Virginia, Maryland) became valuable commodities to be sold to the booming cotton states. Between 1820 and 1860 an estimated 1 million enslaved people were sold in interstate trade, one-third of all marriages broken.