There are 6 US Post Offices in Mitchell County serving a total of 6,578 residents equating to 1,096 residents per post office. It's estimated that approximately 10,499 packages are handled across the 6 county post offices annually. Mitchell County (standard abbreviation: MC) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 6,373. The largest city and county seat is Beloit."