Johnson -- U.S. County in Iowa Population (2000): 111006 Housing Units (2000): 45831 Land area (2000): 614.479195 sq. miles (1591.493741 sq. km) Water area (2000): 8.870559 sq. miles (22.974641 sq. km) Total area (2000): 623.349754 sq. miles (1614.468382 sq. km) Located within: Iowa (IA), FIPS 19 Location: 41.674915 N, 91.568871 W Headwords: Johnson Johnson, IA Johnson County Johnson County, IA