In 1856, a new community named Wilson came into existence but soon the name changed to Illiopolis. It was, until recently, considered to be the geographical center of the state and was, therefore, given serious consideration as a location for the state capital.

From 1941-1945, Illiopolis was the site of a federal Ordnance plant where munitions were produced for World War II. The area covered 19,200 acres and employed 9,700 people from far and near. Those living in that area were required to leave, but were allowed to return at the conclusion of the war. Some returned; many did not.

From the beginning, Illiopolis was an agricultural community and all the businesses were directly, or indirectly, related to farming. As time passed and the population increased, it became a self-sufficient small city with lawyers, doctors, dentists, veterinarians, barbers, hairdressers, automobile dealers, auto mechanics, service stations, grain elevators, grocery stores, hardware stores, restaurants, taverns, a blacksmith shop, a canvas shop, a movie theater, and numerous social groups.

​Many of these business and services are gone as the result of the increased use of the automobile and the improved highway system.