Mountrail County, North Dakota

Mountrail County
Mountrail County Courthouse in Stanley
Location within the U.S. state of North Dakota
North Dakota's location within the U.S.
Coordinates: 48°12′36″N 102°21′54″W / 48.210073°N 102.364895°W / 48.210073; -102.364895
Country United States
State North Dakota
FoundedJanuary 4, 1873 (created)
November 8, 1892 (eliminated)
January 16, 1909 (re-created)
January 29, 1909 (organized)
SeatStanley
Largest cityNew Town
Area
  Total
1,941.419 sq mi (5,028.25 km2)
  Land1,825.163 sq mi (4,727.15 km2)
  Water116.256 sq mi (301.10 km2)  5.99%
Population
 (2020)
  Total
9,809
  Estimate 
(2024)
9,474
  Density5.190/sq mi (2.004/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Area code701
Congressional districtAt-large
Websiteco.mountrail.nd.us

Mountrail County is a county in the northwestern part of North Dakota, United States. As of the 2020 census, the population was 9,809, and was estimated to be 9,474 in 2024. The county seat is Stanley and the largest city is New Town.

The county was originally created in 1873, then removed in 1892, annexed by Ward County. It was re-created and organized in 1909.

The county is home to the headquarters of the Three Affiliated Tribes of the Mandan, Hidatsa, and Arikara people, and a large part of the county belongs to the tribe's Fort Berthold reservation.