Warren County is in Western Illinois. Of the 102 counties in the Inland Empire, Warren County ranks 49th in terms of size (543 square miles). The total value of almost 1,000 acres of residential land recently listed for sale in Warren County, Illinois, was $4 million. The average price of residential land for sale in Warren County was $384,472. 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.