The term West was applied to the region in the British colonial period and in the early years of the United States. By the early 19th century, anything west of Appalachia was considered the West; over time that moniker moved to west of the Mississippi River. During the colonial period, the upper-Mississippi watershed including the Missouri and Illinois River valleys was the setting for the 17th and 18th century French settlements of the Illinois Country.[5] A region north of the Ohio River was sometime called Ohio Country.
In 1787, the Northwest Ordinance was enacted, creating the Northwest Territory, which was bounded by the Great Lakes and the Ohio and Mississippi Rivers. The Northwest Territory (1787) was one of the earliest territories of the United States, stretching northwest from the Ohio River to northern Minnesota and the upper-Mississippi. Because the Northwest Territory lay between the East Coast and the then-far-West, the states carved out of it were called the Northwest. The states of the "old Northwest" are for the most part now called the "East North Central States" (excluding upper Minnesota) by the United States Census Bureau, with the "Great Lakes region" (which includes all of Minnesota) being also a popular term. The states just west of the Mississippi River and the Great Plains states are called the "West North Central States" by the U.S. Census Bureau.[6] Some entities in the Midwest have "Northwest" in their names for historical reasons, such as Northwestern University in Illinois.[7]