There are 3 US Post Offices in Hanson County serving a total of 2,701 residents equating to 900 residents per post office. It's estimated that approximately 4,311 packages are handled across the 3 county post offices annually. Hanson County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 3,331. Its county seat is Alexandria. The county was founded in 1871 and organized in 1873. It was named for Joseph R. Hanson, clerk of the first legislature. Hanson County is part of the Mitchell, SD Micropolitan Statistical Area."