Of 102 counties in the state, Greene County ranks 48th by size (546 square miles). Greene County is in Western Illinois. A recent survey of Land Network data includes roughly 1,000 acres of undeveloped land for sale in Illinois's Greene County, which is valued at a combined $2 million. Browse all Greene County undeveloped acreage for sale on the Land Network to find your next commercial property or land investment. The most common type of land for sale by combined acreage in Greene County is house.