Land for sale in Union County, Indiana, recently totaled around $3 million and nearly 1,000 acres. Union County ranks 91st out of 92 counties in the state for the total acreage of land currently advertised for sale. Of all locations in Union County with farms and rural land for sale, Liberty had the most land for sale. Union County is the 90th largest county (165 square miles) in Indiana. It's located in the East Indiana region of the state.