A total of almost 1,000 acres were listed for sale in Putnam County, Illinois, recently, representing a combined nearly $700,000 in Putnam County farmsand rural real estate for sale. Putnam County ranks 95th out of 102 counties in the Prairie State for the combined amount of land currently advertised for sale. Putnam had the most land for sale. Putnam County is the 102nd largest county (172 square miles) in Illinois. It's located in the Western Illinois region of the state.