The Northwest Territory was established by the Northwest Ordinance on lands that that later became Indiana, Ohio, Illinois, Michigan, Wisconsin and part of Minnesota. The territory marked the the nation’s first post-colonial organized territory. The territory ceased to exist on March 1, 1803 when other territories were made from the land it contained.
At first, the land in the Territory was absorbed first into Indiana Territory and Ohio. Indiana territory was much larger than the state of Indiana today. Indiana Territory existed from July 4, 1800, to December 11, 1816, ending when Indiana became a state.
Book: Charles Kendall Adams, A History of the United States (Boston, MA: Allyn and Bacon, 1909) pg 189; Map Credit: Courtesy the private collection of Roy Winkelman
Map Courtesy of: Indiana History Blog, (blog.history.in.gov)