Jersey -- U.S. County in Illinois Population (2000): 21668 Housing Units (2000): 8918 Land area (2000): 369.157434 sq. miles (956.113325 sq. km) Water area (2000): 7.861732 sq. miles (20.361792 sq. km) Total area (2000): 377.019166 sq. miles (976.475117 sq. km) Located within: Illinois (IL), FIPS 17 Location: 39.083608 N, 90.342138 W Headwords: Jersey Jersey, IL Jersey County Jersey County, IL