Day County is in Glacial Lakes & Prairies South Dakota. Of the 66 counties in the Coyote State, Day County is 28th in terms of its size (1,091 square miles). Day County, South Dakota, has about 1,000 acres of residential land for sale based on recent Land Network data. The combined market value of land for sale here was approximately $4 million. The average price of residential land for sale in Day County was $444,877. The economy here is largely agricultural. 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.