Gregory -- U.S. County in South Dakota Population (2000): 4792 Housing Units (2000): 2405 Land area (2000): 1015.934636 sq. miles (2631.258515 sq. km) Water area (2000): 37.511128 sq. miles (97.153372 sq. km) Total area (2000): 1053.445764 sq. miles (2728.411887 sq. km) Located within: South Dakota (SD), FIPS 46 Location: 43.183400 N, 99.205492 W Headwords: Gregory Gregory, SD Gregory County Gregory County, SD