There are 3 US Post Offices in Aurora County serving a total of 2,605 residents equating to 868 residents per post office. It's estimated that approximately 4,158 packages are handled across the 3 county post offices annually. Aurora County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 2,710. Its county seat is Plankinton. The county was created in 1879 and organized in 1881."