Douglas -- U.S. County in South Dakota Population (2000): 3458 Housing Units (2000): 1453 Land area (2000): 433.527334 sq. miles (1122.830594 sq. km) Water area (2000): 0.604477 sq. miles (1.565588 sq. km) Total area (2000): 434.131811 sq. miles (1124.396182 sq. km) Located within: South Dakota (SD), FIPS 46 Location: 43.376691 N, 98.357179 W Headwords: Douglas Douglas, SD Douglas County Douglas County, SD