[3][4] Oliver County is included in the Bismarck, North Dakota Metropolitan Statistical Area.

The northeastern/eastern boundary of Oliver County is delineated by the Missouri River as it flows southeastward after leaving Lake Sakakawea.

The county terrain consists of rolling hills, mostly devoted to agriculture.

[5] The terrain slopes to the east, with the highest point a hill near its southwestern corner, at 2,382 ft (726 m) ASL.

In terms of ancestry, 66.8% were German, 19.3% were Norwegian, 7.6% were Russian, 6.3% were English, and 4.4% were American.

In only one national election since 1936 has the county selected the Democratic Party candidate (as of 2024).