The total value of land for sale in Mason County, Illinois, recently on Land.com was around $7 million. This represents nearly 1,000 acres of farms and rural real estate for sale in Mason County. Mason County ranks 80th in the Prairie State for the total number of acres of land currently advertised for sale. Among cities in Mason County with land and rural real estate for sale, Havana had the most land for sale. Mason County is Illinois's 47th biggest county (563 square miles). It's located in the Western Illinois region of Illinois.