Oliver is a county in North Dakota, United States, on the west bank of the Missouri River northwest of Bismarck. It had a population of 1,877 at the 2020 census and covers 731 square miles (1,893 km2), centred near 47°07′N 101°20′W.
Center is the county seat, and its postal code is 58530. Oliver County has one incorporated city and five unincorporated communities, and it sits in the Central time zone.
Towns & Villages in Oliver County
Oliver County has one incorporated city — Center, the county seat — and a handful of unincorporated places scattered along the Missouri River and the county’s farm-to-market roads. None of the others has ever incorporated, so they carry no separate government or census population.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Center | City · seat | 588 | 58530 |
| Fort Clark | Unincorp. | — | 58530 |
| Hannover | Unincorp. | — | 58530 |
| Hensler | Unincorp. | — | 58530 |
| Otter Creek | Unincorp. | — | — |
| Price | Unincorp. | — | — |
| Sanger | Unincorp. | — | 58631 |
Fort Clark, just south of Center, sits next to the Fort Clark Historic Site, a former fur-trading post and Mandan/Hidatsa village on the National Register of Historic Places. Sanger, in the county’s northeast corner, uses its own rural ZIP code rather than Center’s; the rest of the unincorporated places share Center’s 58530.
ZIP Codes
- 58530 — Center (also serves Fort Clark, Hannover and Hensler)
- 58631 — Sanger
Otter Creek and Price have no ZIP code of their own; mail there is handled through Center or a neighboring county’s post office.
Geography
Oliver County lies in south-central North Dakota, split by the Missouri River and the Lake Sakakawea/Garrison Dam system upstream. The eastern part of the county drains toward the river’s Washburn bottomlands, while the west rises into rolling, lightly wooded prairie. Water covers about 1.2 percent of the county’s area. The county borders McLean County to the northeast, Burleigh County to the east, Morton County to the south, and Mercer County to the northwest.
Neighboring counties: McLean County (northeast), Burleigh County (east), Morton County (south), and Mercer County (northwest).
Demographics
Oliver County counted 1,877 residents at the 2020 census, making it one of North Dakota’s smallest counties by population. Center, the county seat, is the largest place with 588 residents; Fort Clark and Hannover are the next-largest named communities, though neither reports a separate census population. Median household income in Oliver County runs close to the North Dakota median of $76,525, reflecting the county’s mix of farm income and public-sector jobs. With land area of about 722 square miles, the county’s population density is roughly 2.6 people per square mile — sparse even by North Dakota standards.
Economy & Local Life
Agriculture drives Oliver County’s economy — wheat, corn, soybeans, and cattle ranching on the upland prairie, supplemented by county and school-district government jobs based in Center. The Missouri River bottomland historically supported some of the richest farmland in the county, and a share of residents commute south to Bismarck-Mandan for work. The Fort Clark Historic Site draws a small but steady stream of history-minded visitors each summer.
History
Oliver County was created on April 14, 1885, and organized a month later, on May 18, 1885, carved from Dakota Territory land ahead of North Dakota statehood in 1889. It was named for Harry S. Oliver, a Republican politician from Lisbon, North Dakota, who had no other direct connection to the county. Long before the county existed, the Fort Clark site near the Missouri River was a major Mandan and later Arikara village, and the American Fur Company’s trading post there operated through the mid-1800s until a smallpox epidemic and the site’s abandonment.
Getting There
North Dakota Highways 25, 31, 48, 200A and 1806 cross Oliver County, linking Center to the river towns and to U.S. 83 to the east.
- Bismarck — about 30 miles south
- Washburn (McLean County seat) — about 20 miles northeast
- Hazen (Mercer County seat) — about 20 miles northwest
- Mandan — about 35 miles south
The nearest commercial airport is Bismarck Municipal Airport (BIS), roughly 30 miles south of Center.
Frequently Asked Questions
Where is Oliver County?
It is in south-central North Dakota, along the west bank of the Missouri River northwest of Bismarck.
What is the population of Oliver County?
1,877 people, per the 2020 census.
How big is Oliver County?
731 square miles (1,893 km2), of which about 8.7 square miles is water.
What is the county seat of Oliver County?
Center, the county’s only incorporated city, with 588 residents.
How many towns are in Oliver County?
One incorporated city (Center) and five unincorporated communities: Fort Clark, Hannover, Hensler, Otter Creek, Price and Sanger.
What ZIP codes are in Oliver County?
58530 (Center and most of the county) and 58631 (Sanger).
What is Fort Clark known for?
It was a Mandan and Arikara village site and later a 19th-century American Fur Company trading post, now preserved as a state historic site.
More counties in this state: Towns and villages in North Dakota.