Williams County
Also known as Williams County, North Dakota, Williams County, ND
county in North Dakota, United States
Key facts
- Country
- United States
- State
- North Dakota
- Founded
- March 2, 1891 (created), December 8, 1891 (organized)
- Named after
- Erastus Appleman Williams
- Seat
- Williston
- Largest city
- Williston
- Total
- 2,147.808 sq mi (5,562.80 km )
- Land
- 2,077.600 sq mi (5,380.96 km )
- Water
- 70.208 sq mi (181.84 km ) 3.27%
- Estimate 2025
- 41,767
- Density
- 19.71/sq mi (7.610/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
Article
Williams County is located on the western border of the U.S. state of North Dakota, next to Montana. As of the 2020 census, the population was 40,950, and was estimated to be 41,767 in 2025, making it the fifth-most populous county in North Dakota. The county seat and the largest city is Williston.
The Williston Micropolitan Statistical Area includes all of Williams County. It is bordered on the south by the upper Missouri River, whose confluence with its tributary Yellowstone River is located just east of the border with Montana.