Johnson County is in Southern Illinois. Of the 102 counties in the Prairie State, Johnson County ranks 84th in terms of size (348 square miles). Johnson County, Illinois, includes approximately 1,000 acres of residential land for sale based on recent Land Network data. The combined market value of farms and rural land for sale here was around $7 million. The average price of residential land for sale in Johnson County was $470,907. 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.