There are 20 US Post Offices in Mingo County serving a total of 27,936 residents equating to 1,397 residents per post office. It's estimated that approximately 44,589 packages are handled across the 20 county post offices annually. Mingo County is a county located in the U.S. state of West Virginia. As of the 2010 census, the population was 26,839. Its county seat is Williamson. Created in 1895, Mingo is West Virginia's newest county, named for the historic Iroquoian Mingo people."