Clay -- U.S. County in Indiana Population (2000): 26556 Housing Units (2000): 11097 Land area (2000): 357.617036 sq. miles (926.223832 sq. km) Water area (2000): 2.775799 sq. miles (7.189285 sq. km) Total area (2000): 360.392835 sq. miles (933.413117 sq. km) Located within: Indiana (IN), FIPS 18 Location: 39.439101 N, 87.119952 W Headwords: Clay Clay, IN Clay County Clay County, IN