Williams County is located on the western border of the U.S. state of North Dakota, next to Montana.

The first, created in 1873, was located south of the Missouri River near where Dunn and Mercer counties are today.

[4] In June 2014, lightning struck a Williams County Oasis Petroleum saltwater disposal facility.

[5] Williams County lies on the west edge of North Dakota.

The Missouri River flows eastward along the county's south boundary line from the confluence with its tributary Yellowstone River, located on the Dakota side of the state border with Montana.

The terrain consists of isolated hills amid rolling, hilly, semi-arid stretches.

Lake Sakakawea, a reservoir on the Missouri River, is situated on the southern boundary of the county.

The Fort Union Trading Post National Historic Site is located in Williams County along the Missouri River on the Montana border.

[14] The population density was 19.7 inhabitants per square mile (7.6/km2) There were 20,227 housing units.

In no national election since 1964 has the county selected the Democratic Party candidate.