There are 7 US Post Offices in Turner County serving a total of 8,003 residents equating to 1,143 residents per post office. It's estimated that approximately 12,774 packages are handled across the 7 county post offices annually. Turner County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 8,347. Its county seat is Parker. The county was established in 1871 and named for Dakota Territory official John W. Turner. Turner County is part of the Sioux Falls, SD Metropolitan Statistical Area."