Washington County is in Southern Illinois. Of the 102 counties in the state, 563-square-mile Washington County ranks 46th by size. There is approximately 1,000 acres of residential land for sale in Washington County, Illinois, based on recent Land Network data, making it the most common type of land for sale in Washington County. The combined market value of land and rural real estate for sale here is almost $3 million. The average price of residential acreage for sale in Washington County was $303,666. Browse all residential land and rural property for sale in Illinois 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.