Madison, Wisconsin is the capital of the Midwestern United States. It is a city of approximately 250, 000 people and is the second most populous city in the state. Omaha, Nebraska is the largest city in the state and is located on the Missouri River. It has a population of over 400, 000 people. Topeka, Kansas is the capital of the state and is located on the Kansas River. It has a population of around 127, 000 people. Pierre, South Dakota is the capital of the state and is located on the Missouri River. It has a population of around 14, 000 people. All four cities are important capitals of the Midwestern United States.