There are 3 US Post Offices in Sheridan County serving a total of 1,079 residents equating to 360 residents per post office. It's estimated that approximately 1,722 packages are handled across the 3 county post offices annually. Sheridan County is a county located in the U.S. state of North Dakota. As of the 2010 census, the population was 1,321, making it the third-least populous county in North Dakota. Its county seat is McClusky. The county was formed by the 1872\u20131873 territorial legislature but was attached to McLean County for judicial purposes until the 1908 general election, when voters decided to split Sheridan from McLean County entirely. The name comes from Civil War General Philip Henry Sheridan. The county government was first organized on December 24, 1908."