On what date did Congress enact the Northwest Ordinance of 1787?

Congress enacted the Northwest Ordinance of 1787 on July 13, 1787.

The Confederation Congress passed the law while the Constitutional Convention was meeting in Philadelphia. It created the Northwest Territory, covering land north and west of the Ohio River and east of the Mississippi River below the Great Lakes. The territory later contributed land to Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota.

The ordinance established a process for governing territories and admitting new states. It set a population pathway from an appointed territorial government to an elected legislature and eventual statehood. It also prohibited slavery in the Northwest Territory, although the provision did not end slavery elsewhere in the United States.

The measure became an important model for American westward expansion. Rather than allowing existing states to control new lands permanently, it placed the territory under federal administration and anticipated equal admission of new states. The First Congress reaffirmed the ordinance in 1789, after the Constitution created the new federal government.