The Northwest Ordinance (formally An Ordinance for the Government of the Territory of the United States, North-West of the River Ohio and also known as the Ordinance of 1787), enacted July 13, 1787, was an organic act of the Congress of the Confederation of the United States. It created the Northwest Territory, the new nation's first organized incorporated territories between British North America and the Great Lakes to the north and the Ohio River to the south. The upper Mississippi River formed the territory's western boundary. Pennsylvania was the eastern boundary.
In the 1783 Treaty of Paris, which formally ended the American Revolutionary War, Great Britain ceded the region to the United States. However, the Confederation Congress faced numerous problems gaining control of the land such as the unsanctioned movement of American settlers into the Ohio Valley; violent resistance from the region's indigenous peoples; the continued presence of British outposts in the region and an empty U.S. treasury. The ordinance superseded the Land Ordinance of 1784, which declared that states would one day be formed within the region, and the Land Ordinance of 1785, which described how the Confederation Congress would sell the land to private citizens. Designed to serve as a plan for the development and settlement of the region, the 1787 ordinance lacked a strong central government to implement it. That need was addressed shortly with the formation of the U.S. federal government in 1789. The First Congress reaffirmed the 1787 ordinance and, with slight modifications, renewed it with the Northwest Ordinance of 1789.