Hamilton County is in Southern Illinois. Of the 102 counties in the Land of Lincoln, Hamilton County is 68th in terms of its size (435 square miles). McLeansboro is the county seat of Hamilton County, a mostly agricultural region comprising cornfields and small Midwestern farming communities. This often-overlooked area of southern Illinois is also home to a few surprising attractions, including the country's largest archaeological site,?Cahokia Mounds State Historic Site, over 100 wineries and outdoor recreation like bouldering and mountain biking in 280,000-acre Shawnee National Forest. Browse all Hamilton County forest and timberland for sale on the Land Network to find the right timberland acreage for your commercial or individual investment needs. By overall acreage, house is the most common type of land for sale in Hamilton County.