Johnson County is in Southern Illinois. Of the 102 counties in the Inland Empire, 223,272-acre Johnson County ranks 84th by size. Johnson County, Illinois, includes almost 1,000 acres of residential land for sale based on recent Land Network data. The combined market value of farmsand rural real estate for sale here was roughly $8 million. The average price of residential acreage for sale in Johnson County was $432,705. 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.