On April 2, 1802, Georgia ceded its western territory—the land that would become Alabama and Mississippi—under the condition that slavery would be legal there.

The Northwest Ordinance, passed by Congress in 1787, had laid out the procedures for adding new states to the U.S. that were located in the Northwest Territory (lands above the Ohio River between Pennsylvania and the Mississippi River). The law stipulated that slavery would be banned in these lands.

However, when the State of Georgia agreed to relinquish claims to its western territory (lands below Tennessee between the Chattahoochee River and the Mississippi River), it chose, with the federal government’s agreement, to deviate from the Northwest Ordinance in one major respect: Georgia’s act of cession stated that the Northwest Ordinance “shall, in all its parts, extend to the territory contained in the present act of cession, that article only excepted which forbids slavery.”

Georgia’s cession of its western territory was part of a strategy by the "slave states" to shore up their power. At the time, there were eight "slave states" and eight "free states." By creating new states in which slavery was legal, the U.S. Senate would add senators who supported slavery. In 1790, North Carolina had similarly ceded its western territories to create the "slave states" of Tennessee and Kentucky. As long as the Southern states held enough power in the Senate, they could block federal legislation pertaining to the issue of slavery in Congress.

Because of the slavery clause in Georgia’s act of cession, hundreds of thousands of Black people would become enslaved in Alabama and Mississippi. The enslaved population of Alabama grew from under 40,000 when the cession occurred to over 435,000 in 1860. In Mississippi, the enslaved population grew from under 33,000 to over 435,000 in 1860 as well.