Also found in: Encyclopedia, Wikipedia.
Northwest TerritoryFormerly Old Northwest.
A historical region of the north-central United States extending from the Ohio and Mississippi Rivers to the Great Lakes. The area was ceded to the United States by the Treaty of Paris in 1783. It was officially designated a territory in 1787 and later split up into the territories and present-day states of Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota. Control over the territory was a major issue in the War of 1812.
(Placename) See Old Northwest
the region north of the Ohio River and east of the Mississippi, organized by Congress in 1787, comprising present-day Ohio, Indiana, Illinois, Michigan, Wisconsin, and the E part of Minnesota.