Of 102 counties in the Land of Lincoln, Williamson County ranks 65th in terms of size (444 square miles). Williamson County is in Southern Illinois. A recent survey of Land Network data records approximately 1,000 acres of ranches for sale in Illinois's Williamson County, which is valued at a combined $899,900. Browse all Williamson County ranches for sale on the Land Network to find the ranch that's right for your business or commercial needs, from the sprawling legacy ranch to unbelievable residential ranch for your second home, investment property or retirement nest egg. The most common type of land for sale by combined acreage in Williamson County is residential property.