Land for sale in Monona County recently totaled around $3 million and almost 1,000 acres. Monona County ranks 95th out of 99 counties in the Cyclone State for the total acreage of land currently advertised for sale. Onawa featured the most land for sale. Its economy is defined as agricultural, with 538 farms recorded in the county during the most recent U.S. Census. Farming activities in Monona County generate annual revenues of $23 million, most of which is from crops. Monona County is Iowa's 16th largest county (698 square miles). It's located in the Western Iowa region of Iowa.