Whiteside -- U.S. County in Illinois Population (2000): 60653 Housing Units (2000): 25025 Land area (2000): 684.770119 sq. miles (1773.546391 sq. km) Water area (2000): 12.242187 sq. miles (31.707117 sq. km) Total area (2000): 697.012306 sq. miles (1805.253508 sq. km) Located within: Illinois (IL), FIPS 17 Location: 41.778260 N, 89.867831 W Headwords: Whiteside Whiteside, IL Whiteside County Whiteside County, IL