Petroleum -- U.S. County in Montana Population (2000): 493 Housing Units (2000): 292 Land area (2000): 1653.903684 sq. miles (4283.590695 sq. km) Water area (2000): 20.110830 sq. miles (52.086808 sq. km) Total area (2000): 1674.014514 sq. miles (4335.677503 sq. km) Located within: Montana (MT), FIPS 30 Location: 47.000478 N, 108.290051 W Headwords: Petroleum Petroleum, MT Petroleum County Petroleum County, MT