St. Clair -- U.S. County in Missouri Population (2000): 9652 Housing Units (2000): 5205 Land area (2000): 676.655803 sq. miles (1752.530410 sq. km) Water area (2000): 25.247455 sq. miles (65.390605 sq. km) Total area (2000): 701.903258 sq. miles (1817.921015 sq. km) Located within: Missouri (MO), FIPS 29 Location: 38.051170 N, 93.779268 W Headwords: St. Clair St. Clair, MO St. Clair County St. Clair County, MO