Johnson -- U.S. County in Kansas Population (2000): 451086 Housing Units (2000): 181612 Land area (2000): 476.776035 sq. miles (1234.844210 sq. km) Water area (2000): 3.368987 sq. miles (8.725636 sq. km) Total area (2000): 480.145022 sq. miles (1243.569846 sq. km) Located within: Kansas (KS), FIPS 20 Location: 38.932175 N, 94.753767 W Headwords: Johnson Johnson, KS Johnson County Johnson County, KS