Capital Illinois is a term used to refer to the state of Illinois, which is located in the Midwestern United States. The capital of Illinois is Springfield, and the state is home to several other cities, including Peru (4 letters), Alton (5 letters), and Peoria (6 letters). Peru is a village in LaSalle County, Alton is a city in Madison County, and Peoria is a city in Peoria County. All three cities are located in the central part of the state and are considered part of the Capital Illinois region.