There are 5 US Post Offices in Mercer County serving a total of 8,502 residents equating to 1,700 residents per post office. It's estimated that approximately 13,570 packages are handled across the 5 county post offices annually. Mercer County is a county located in the U.S. state of North Dakota. As of the 2010 census, the population was 8,424. Its county seat is Stanton. The county was created by the 1874-1875 territorial legislature and was named for William Henry Harrison Mercer (1844\u20131901), an early rancher who settled north of Bismarck in 1869. The county government was first organized on August 4, 1884."