Which 1787 law prohibited slavery in the United States territory north of the Ohio River?

The Northwest Ordinance of 1787 prohibited slavery in the United States territory north of the Ohio River.

Enacted by the Confederation Congress on July 13, 1787, the ordinance organized the Northwest Territory, a vast region that later became Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota. It established a process by which territories could develop and eventually enter the Union as states.

Article 6 declared that “there shall be neither slavery nor involuntary servitude” in the territory, although it included a fugitive-slave provision. The measure therefore restricted legal slavery in the territory without abolishing slavery nationwide.

The Northwest Ordinance is sometimes confused with the Missouri Compromise of 1820, which addressed slavery’s expansion in lands acquired through the Louisiana Purchase. The ordinance was earlier and applied specifically to the territory northwest of the Ohio River.