Hartford is a village in Madison County, Illinois, United States, on the Mississippi River near the mouth of the Missouri River. The population was 1,185 at the 2020 census, down from 1,429 in 2010. Lewis and Clark spent the winter of 1803-04 there, near what has been designated the Lewis and Clark State Historic Site.

Madison County is a county in the U.S. state of Illinois. It is a part of the Metro East in southern Illinois. According to the 2020 census, it had a population of 264,776, making it the eighth-most populous county in Illinois and the most populous in the southern portion of the state. The county seat is Edwardsville, and the largest city is Granite City.