The Northwest Ordinance of 1787 created the Northwest Territory, the United States’ first organized incorporated territory. Congress enacted the ordinance on July 13, 1787, for lands north and west of the Ohio River.
The territory covered much of the modern American Midwest, including areas that later became Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota. The ordinance established a process for governing the region and eventually admitting new states on an equal footing with the original states.
It also prohibited slavery in the territory, although the law did not immediately end slavery elsewhere in the United States. The Northwest Ordinance built on earlier land laws and set an important precedent for westward expansion. The First Congress reaffirmed it, with modifications, in 1789.