Douglas -- U.S. County in Illinois Population (2000): 19922 Housing Units (2000): 8005 Land area (2000): 416.862108 sq. miles (1079.667857 sq. km) Water area (2000): 0.557141 sq. miles (1.442988 sq. km) Total area (2000): 417.419249 sq. miles (1081.110845 sq. km) Located within: Illinois (IL), FIPS 17 Location: 39.769979 N, 88.236661 W Headwords: Douglas Douglas, IL Douglas County Douglas County, IL