The Northwest Ordinance of 1787 was created to establish a form of government for what was then known as the Northwest Territory. The area covered the present states of Illinois, Indiana, Michigan, Ohio and Wisconsin as well as a portion of Minnesota.
The Northwest Ordinance had three central provisions. It established that the territory must have at least three but no more than five states, established a procedure for admitting these new states to the Union and created a bill of rights for the territory. The bill of rights prohibited slavery, ensured religious freedom and established the right to a jury trial and to a writ of habeas corpus among other rights.
The 1787 ordinance was shortly replaced by a new version in 1789. This new version was mostly identical, with small changes made to bring it in line with the newly adopted federal Constitution.
The ordinance had a very important legacy for several reasons. It established the formal process by which the United States government would expand westward across the continent and add new states to the Union. The prohibition of slavery also effectively set the Ohio River as the boundary between slaveholding and nonslaveholding territories in the region.