Clay -- U.S. County in Iowa Population (2000): 17372 Housing Units (2000): 7828 Land area (2000): 568.887016 sq. miles (1473.410544 sq. km) Water area (2000): 3.627150 sq. miles (9.394276 sq. km) Total area (2000): 572.514166 sq. miles (1482.804820 sq. km) Located within: Iowa (IA), FIPS 19 Location: 43.103200 N, 95.156090 W Headwords: Clay Clay, IA Clay County Clay County, IA