The 18th Congressional District of Illinois covers central and western Illinois, including all or part of Jacksonville, Peoria, Quincy, and Springfield. Republican Aaron Schock had represented the district since January 2009, but resigned March 31, 2015. Special elections were called to select Schock's replacement, with a primary on July 7 and the main election on September 10, 2015, which was won by Republican State Senator Darin LaHood. Abraham Lincoln served much of the area that now lies within the 18th district for a single term; it was numbered as the 7th district at the time.