Rock Island County is in Western Illinois. Of the 102 counties in the Inland Empire, 288,824-acre Rock Island County ranks 62nd by size. Recent listings of residential land for sale in Illinois's Rock Island County totals almost 1,000 acres and a combined market value of roughly $7 million. The most common type of land for sale by combined acreage in Rock Island County is undeveloped land. The average price of residential land for sale in Rock Island County was $399,594. 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.