What 1787 law created a process for territories north of the Ohio River to become U.S. states?

The Northwest Ordinance created a process for territories north of the Ohio River to become U.S. states.

Congress adopted the Northwest Ordinance on July 13, 1787, under the Articles of Confederation. It organized the Northwest Territory, a region that later became all or part of Ohio, Indiana, Illinois, Michigan, Wisconsin, and Minnesota. The ordinance established a territorial government and described a path from appointed administration to elected government and statehood.

The measure barred slavery in the territory, making it an important early federal restriction on slavery's expansion. It also guaranteed religious freedom, encouraged public education, protected certain legal rights, and recognized that Indigenous land could not be taken without consent. Enforcement of those principles was uneven, especially regarding Native nations.

The Northwest Ordinance is sometimes confused with the Constitution, which was drafted later in 1787 and replaced the Articles of Confederation. The ordinance was not a constitution for the whole United States. Instead, it became a durable framework for incorporating western territories into the Union on equal footing with existing states.