Warren County is in Western Illinois. Of the 102 counties in the state, 543-square-mile Warren County ranks 49th by size. The total value of roughly 1,000 acres of residential land and property recently listed for sale in Warren County, Illinois, was around $4 million. The average price of residential acreage for sale in Warren County was $282,476. 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.