http://www.historychannel.com/tdih/tdih.jsp?category=general&month=10272955&day=10272967The U.S. Congress passes an act to "prohibit the importation of slaves into any port or place within the jurisdiction of the United States...from any foreign kingdom, place, or country."
After the war, as slave labor was not a crucial element of the Northern economy, most Northern states passed legislation to abolish slavery. However, in the South, the invention of the cotton gin in 1793 made cotton a major industry and sharply increased the need for slave labor. Tension arose between the North and the South as the slave or free status of new states was debated. In January 1807, with a self-sustaining population of over four million slaves in the South, some Southern congressmen joined with the North in voting to abolish the African slave trade, an act that became effective January 1, 1808. The widespread trade of slaves within the South was not prohibited, however, and children of slaves automatically became slave themselves, thus ensuring a self-sustaining slave population in the South.