The value of all farms, rural land, hunting land and other land for sale in Illinois's DeKalb County recently was nearly $90 million, representing a total of 2,176 acres of land for sale in DeKalb County. DeKalb County ranks 19th out of 102 counties in Illinois for the total number of acres of land currently advertised for sale. Sycamore had the most land for sale. Government and state-level services are the main economic drivers in DeKalb County. DeKalb County is the 31st biggest county (634 square miles) in Illinois. It's located in the Northern Illinois region of Illinois.