There are 3 US Post Offices in Mcpherson County serving a total of 2,238 residents equating to 746 residents per post office. It's estimated that approximately 3,572 packages are handled across the 3 county post offices annually. McPherson County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 2,459. Its county seat is Leola."