The Northwest Ordinance was created in 1787. Its purpose was to organize the procedures to be followed as new territory was opened for settlement and eventual admission into the United States in the form of new states.
The Ordinance of 1787 (its official title) directly addressed the land between the Ohio and Mississippi Rivers and north to the Great Lakes. A governor, secretary, and three judges were appointed to provide initial governmental supervision as the land was opened for development by settlers. When the population in the territory reached 5,000 inhabitants, the Ordinance authorized the local election of a territorial legislature and the designation of a non-voting representative from the territory to the House of Representatives in Washington. When a specific area within the territory reached a population of 60,000, that area could begin the process of applying for admission to the Union as a new state. In accordance with the Ordinance's directions, the territory could be divided into three to five states. Eventually, the states created from the territory covered by the Ordinance were Illinois, Indiana, Michigan, part of Minnesota, Ohio, and Wisconsin.
The Northwest Ordinance established the framework for procedures that were followed as new territory and new states were added to the United States throughout its years of physical expansion.