Marshall -- U.S. County in Illinois Population (2000): 13180 Housing Units (2000): 5914 Land area (2000): 386.062142 sq. miles (999.896316 sq. km) Water area (2000): 12.453065 sq. miles (32.253288 sq. km) Total area (2000): 398.515207 sq. miles (1032.149604 sq. km) Located within: Illinois (IL), FIPS 17 Location: 41.048508 N, 89.295467 W Headwords: Marshall Marshall, IL Marshall County Marshall County, IL