Knox County is in Western Illinois. Of the 102 counties in the Inland Empire, 460,704-acre Knox County ranks 23rd by size. Recent Land Network data totals around 1,000 acres of residential land for sale in Illinois's Knox County, which is valued at a combined $3 million. The average price of residential land for sale in Knox County was $241,739. 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.