THIS PAGE IS CURRENTLY UNDER CONSTRUCTION. Illinois is the 21st state in the United States. It became a state in 1818. The capital is Springfield and the largest city is Chicago. It was formed from the Northwest Territory. Retrieved from "https://amazing-everything.fandom.com/wiki/Illinois?oldid=47612" Categories: States Articles in need of expansion United States Article stubs Community content is available under CC-BY-SA unless otherwise noted.