The combined value of land for sale in Illinois's Mercer County recently on Land.com was almost $4 million. This represents 1,000 acres of farms and rural real estate for sale in Mercer County. Mercer County ranks 65th out of 102 counties in the Inland Empire for the total acreage of land currently advertised for sale. Of all locations in Mercer County with farms, hunting land and other rural land and acreage for sale, Sherrard featured the most land for sale. Mercer County is Illinois's 44th biggest county (568 square miles). It's located in the Western Illinois region of the state.