Union County is in Southeast South Dakota. Of the 66 counties in the Coyote State, Union County ranks 62nd in terms of size (298,961 acres). There is almost 1,000 acres of residential land for sale in South Dakota's Union County based on recent Land Network data, making it the most common type of land for sale in Union County. The combined market value of ranches, farms, hunting land and other rural land and acreage for sale here is $21 million. The average price of residential land for sale in Union County was $521,884. Browse all residential land and rural property for sale in South Dakota to find residential land and properties that suit your lifestyle needs, from existing residential homes and estates to land ready for future residential-property development.