Land for sale in Canyon County, Idaho, recently totaled approximately $627 million and approximately 5,000 acres. Canyon County ranks third out of 44 counties in the Gem State for the total number of acres of land currently advertised for sale. Among cities in Canyon County with land and rural real estate for sale, Caldwell featured the most land for sale. Canyon County is Idaho's 38th biggest county (603 square miles). It's located in the Southwestern Idaho region of Idaho.