Petroleum County, Montana

Petroleum County is a county found in the U.S. state of Montana. As of the 2020 United States Census, 496 people lived there,^[1] making it the least populous county in Montana and the eighth-least populous in the United States.^[2] Its county seat is Winnett.^[3] The county's area was split from Fergus County to become the last of Montana's 56 counties to be organized.^[4][5]

Petroleum County
County
Petroleum County Courthouse in Winnett
Location within the U.S. state of Montana
Montana's location within the U.S.
Coordinates: 47°07′N 108°16′W
Country	United States
State	Montana
Founded	February 25, 1925
Named for	Petroleum fields
Seat	Winnett
Largest town	Winnett
Area
• Total	1,674 sq mi (4,340 km2)
• Land	1,655 sq mi (4,290 km2)
• Water	19 sq mi (50 km2)  1.1%
Population  (2020)
• Total	496
• Density	0.30/sq mi (0.11/km2)
Time zone	UTC−7 (Mountain)
• Summer (DST)	UTC−6 (MDT)
Congressional district	2nd
Website	petroleumcountymt.org
Montana county number 55