There are 13 US Post Offices in Mclean County serving a total of 9,856 residents equating to 758 residents per post office. It's estimated that approximately 15,731 packages are handled across the 13 county post offices annually. McLean County (/m\u0259\u02c8kle\u026an/ m\u0259-KLAYN) is a county located in the U.S. state of North Dakota. As of the 2010 census, the population was 8,962. Its county seat is Washburn. The county was created by the 1883 territorial legislature and organized on November 1, 1883. It was named for John A. McLean, a prominent citizen and the first mayor of Bismarck, North Dakota."