The value of all farms, hunting land and other rural land and acreage for sale in Mercer County, Illinois, recently was approximately $4 million, representing a total of 114 acres of land for sale in Mercer County. Mercer County ranks 70th in the Inland Empire for the total number of acres of land currently advertised for sale. Of all locations in Mercer County with farms, rural land, hunting land and other land for sale, Alexis had the most land for sale. Mercer County is Illinois's 44th largest county (568 square miles). It's located in the Western Illinois region of the state.