Illinois is ranked 24th in size I the US covering a total area of 56,345 sq mi (145,934 sq km), of which land comprises 55,645 sq mi (144,120 sq km) and inland water 700 sq mi (1,814 sq km). Situated in the eastern north-central US, Illinois is bounded on the North by Wisconsin; on the East by Lake Michigan and Indiana; on the South East and South by Kentucky; and on the West by Missouri and Iowa.

The geographic center of Illinois is in Logan County, 28 mi (45 km) NE of Springfield, the capital of Illinois.