A total of almost 1,000 acres were listed for sale in Clay County, South Dakota, recently, representing a total value of nearly $13 million in Clay County farms and ranches for sale. Clay County ranks 13th out of 66 counties in South Dakota for the combined amount of land currently advertised for sale. Of all farms, ranches, and rural real estate for sale in Clay County, Vermillion had the most land for sale. From an economic perspective, government and state-level services contribute most to Clay County's overall GDP. Clay County is South Dakota's 66th biggest county (417 square miles). It's located in the Southeast South Dakota region of South Dakota.