The value of all land and rural real estate for sale in Illinois's DeKalb County recently was $97 million, representing a total of 2,524 acres of land for sale in DeKalb County. DeKalb County ranks 18th in the Land of Lincoln for the total acreage of land currently advertised for sale. Of all farms and rural real estate for sale in DeKalb County, Sycamore featured the most land for sale. From an economic perspective, government and state-level services contribute most to DeKalb County's overall GDP. DeKalb County is the 31st largest county (634 square miles) in Illinois. It's located in the Northern Illinois region of the state.