Land for sale in Grant County, South Dakota, recently totaled $2 million and nearly 1,000 acres. Grant County ranks 42nd out of 66 counties in the state for the combined amount of land currently advertised for sale. Of all locations in Grant County with land for sale, Milbank had the most land for sale. Grant County is South Dakota's 48th largest county (687 square miles). It's located in the Glacial Lakes & Prairies South Dakota region of the state.