The value of farms, ranches, and rural real estate for sale in Madison County, Idaho, recently on Land.com was $33 million. This represents 3,000 acres of land for sale in Madison County. Madison County ranks 42nd out of 44 counties in the Gem State for the total acreage of land currently advertised for sale. Of all farms, ranches, hunting land and other land for sale in Madison County, Rexburg featured the most land for sale. Madison County is Idaho's 42nd largest county (473 square miles). It's located in the Eastern Idaho region of Idaho.