St. Charles is an affluent Chicago suburb in Kane and DuPage counties of Illinois, United States, and is roughly 40 miles (64 km) west of Chicago on Illinois Route 64. According to a 2004 census estimate, the city has a total population of 32,134. The official city slogan is Pride of the Fox, after the Fox River that runs through the center of town. St. Charles is part of a tri-city area along with Geneva and Batavia, all far-western suburbs of similar size and relative socioeconomic condition.

After the Black Hawk War in 1832 opened the Fox River valley to white settlement, Evan Shelby and William Franklin staked the first claim in what is now St. Charles in 1833. They came back in 1834 with their families from Indiana, and were joined by over a dozen other families later that year. The township was initially known as Charleston, but this name was already taken by the downstate city of Charleston, Illinois so the name of Saint Charles (suggested by S. S. Jones, a lawyer) was adopted in 1839. St. Charles became incorporated as a city in 1874. Rumors are that Abraham Lincoln's wife visted friends in St. Charles and talked somewhere downtown.

Several "stations" of the slavery-era Underground Railroad were in St. Charles homes, complete with tunnels and false doorways; there was also an open abolitionist group called the Kane County Anti-Slavery Society, founded in 1842, with about 180 members.