Warren County is home to Monmouth College. According to the 2017 Census of Agriculture, there were 711 farms in Warren County, spanning 340,985 acres, with an average farm size of 480 acres. The population of Warren County was 17,707 (based on 2010 census). Warren County was named after Dr. Joseph Warren, who was believed to have been the first office to die in the Revolutionary War at the Battle of Bunker Hill in 1775. Warren County’s temperatures range from 15°F during January to 85°F during July. Average monthly precipitation ranges from 1.62" during January to 4.33" during July. If you're looking for land for sale in Warren County, IL, check out Land Pro LLC's current listings below. If there are no current listings in Warren County, take a look at land for sale in neighboring Henry County, and Knox County. You can also view all the Illinois land offered for sale by Land Pro LLC.