The value of farms, ranches, and rural real estate for sale in Big Horn County, Montana, recently on Land.com was nearly $119 million. This represents 100,000 acres of land for sale in Big Horn County. Big Horn County ranks 27th in the Treasure State based on the combined acreage of land for sale among all the counties in Montana. Hardin featured the most land for sale. Mining and mineral extraction-related services are the main economic drivers in this part of Montana. Big Horn County is one of the ten largest counties in Montana (5,016 square miles). It's located in the Southeast Montana region of the state.