The correct option is "Northwest Ordinance of 1787 "
The Ordinance for the Government of the Territory of the United States, Northwest of the Ohio River known as the Northwest Ordinance or the Freedom Ordinance was a law of the Congress of the United States Confederation. The ordinance was approved unanimously on July 13, 1787. The main effect of the ordinance was the creation of the Northwest Territory as the first organized territory of the United States of the region south of the Great Lakes north and west of the River Ohio, and east of the Mississippi River. On August 7, 1789, the Congress of the United States affirmed the Ordinance with slight changes established by the Constitution. Possibly the most important legislation that was passed by the members of the Continental Congress apart from the Declaration of Independence, established the precedence by which the United States expanded westward through North America by the admission of new states rather than by the expansion of existing states. The prohibition of slavery in the territory made the Ohio River the border between the free territories and the slave territories around the Appalachians and the Mississippi River.
