The Midwestern United States, also referred to as the American Midwest or simply the Midwest, is one of the four geographic regions defined by the United States Census Bureau, occupying the northern central part of the United States of America. It was officially named the North Central region by the Census Bureau until 1984.
Though the region is traditionally defined in a number of ways, the Census Bureau's definition consists of 12 states in the north central United States: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin. Illinois is the most populous of the states and North Dakota the least. A 2012 report from the United States Census put the population of the Midwest at 65,377,684. The Midwest is divided by the Census Bureau into two divisions. The East North Central Division includes Illinois, Indiana, Michigan, Ohio and Wisconsin, all of which are also part of the Great Lakes region. The West North Central Division includes Iowa, Kansas, Minnesota, Missouri, North Dakota, Nebraska, and South Dakota, all of which, except for Iowa, Missouri and Minnesota, are located, at least partly, within the Great Plains region of the country. Major rivers in the region include, from east to west, the Ohio River, the Upper Mississippi River, and the Missouri River, constituting the main branches of the northern Mississippi River watershed.
Chicago is the most populated city in the American Midwest and the third most populous in the entire country. Other large Midwest cities include (in order by population): Indianapolis, Columbus, Detroit, Milwaukee, Kansas City, Omaha, Minneapolis, Cleveland, Wichita and St. Louis. Chicago and its suburbs form the largest metropolitan statistical area with 9.8 million people, followed by Metro Detroit, Minneapolis–St. Paul, Greater St. Louis, Greater Cincinnati, Greater Cleveland, Kansas City metro area, and the Columbus metro area.
The term Midwestern has been in use since the 1880s to refer to portions of the central United States. A variant term, Middle West, has been used since the 19th century and remains relatively common. Another term sometimes applied to the same general region is the heartland. Other designations for the region have fallen out of use, such as the Northwest or Old Northwest (from "Northwest Territory") and Mid-America.
Economically the region is balanced between heavy industry and agriculture (large sections of this land area make up the United States' Corn Belt), with finance and services such as medicine and education becoming increasingly important. Its central location makes it a transportation crossroads for river boats, railroads, autos, trucks and airplanes. Politically the region swings back and forth between the parties, and thus is heavily contested and often decisive in elections.
After the sociological study Middletown (1929), which was based on Muncie, Indiana, commentators used Midwestern cities (and the Midwest generally) as "typical" of the nation. The region has a higher employment-to-population ratio (the percentage of employed people at least 16 years-old) than the Northeast, the West, the South, or the Sun Belt states as of 2011.