There are 1 US Post Offices in Oliver County serving a total of 1,193 residents equating to 1,193 residents per post office. It's estimated that approximately 1,904 packages are handled across the 1 county post offices annually. Oliver County is a county located in the U.S. state of North Dakota. As of the 2010 census, the population was 1,846, making it the fifth-least populous county in North Dakota. Its county seat and only city is Center. The county was created by the 1885 territorial legislature and was organized on May 18, 1885. It was named for Harry S. Oliver of Lisbon, North Dakota (1855-1909), a Republican politician and member of the Dakota Territory House of Representatives at the time. Sanger (Raymond) was the county seat from 1885 to 1902, when the title went to Center. Oliver County is included in the Bismarck, ND Metropolitan Statistical Area."