The mission was originally organized as the Northwestern States Mission on 6 May 1878 and headquartered in Chicago, Illinois. The mission name changed to the Northern States Mission on 20 July 1889.
Not to be confused with the Northwestern States Mission organized on 26 July 1897 and headquartered in Portland, Oregon.
The Northern States Mission was renamed as the Illinois Mission on 17 June 1973, at that time it consisted of the state of Illinois, except the Illinois portion of the St. Louis, Missouri Stake. It contained a small strip of eastern Iowa, which included Keosauqua, Fort Madison, and Burlington; plus a small portion of western Indiana around LaPorte, Hammond, and Gary.