Claim: The Midwestern United States includes South Dakota.

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 .   Although the region is often 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 , several of which are located at least partly , within the Great Plains region . Major rivers in the region include , from east to west , the Ohio River , the Upper Mississippi River , and the Missouri River . The region generally lies on the broad Interior Plain between the states occupying the Appalachian Mountain range and the states occupying the Rocky Mountain range .   Chicago is the most populated city in the American Midwest and the third most populous in the entire country . Other large Midwest cities include -LRB- in order by population -RRB- : 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 Cleveland , Greater Cincinnati -LRB- without the Kentucky portion -RRB- , Kansas City metro area , and the Columbus metro area .