Land for sale in South Dakota's Union County recently totaled $29 million and around 2,000 acres. Union County ranks 10th in the state for the total number of acres of land currently advertised for sale. There were four properties listed as sold in Union County through the Land Network Comparable Sales Program. This represented a total value of $2,080,715. Among cities in Union County with farms, ranches, hunting land and other land for sale, Dakota Dunes featured the most land for sale. Union County is the 62nd largest county (467 square miles) in South Dakota. It's located in the Southeast South Dakota region of the state.