Custer -- U.S. County in Montana Population (2000): 11696 Housing Units (2000): 5360 Land area (2000): 3783.126170 sq. miles (9798.251384 sq. km) Water area (2000): 10.090481 sq. miles (26.134225 sq. km) Total area (2000): 3793.216651 sq. miles (9824.385609 sq. km) Located within: Montana (MT), FIPS 30 Location: 46.324144 N, 105.766538 W Headwords: Custer Custer, MT Custer County Custer County, MT