There are 3 US Post Offices in Hughes County serving a total of 17,241 residents equating to 5,747 residents per post office. It's estimated that approximately 27,519 packages are handled across the 3 county post offices annually. Hughes County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 17,022, making it the least populous capital county in the nation. Its county seat is Pierre, the state capital. The county was created in 1873 and organized in 1880. It was named for Alexander Hughes, a legislator. Hughes County is part of the Pierre, SD Micropolitan Statistical Area."