Cities and CDPs with 10,000 or more people •
Belleville – 42,404 •
O'Fallon – 32,289 •
Carbondale – 25,083 •
Charleston – 17,286 •
Mattoon – 16,870 •
Marion – 16,855 •
Fairview Heights – 16,706 •
Mount Vernon – 14,600 •
Shiloh – 14,098 •
Herrin – 12,352 •
Effingham – 12,252 •
Centralia – 12,182 •
Waterloo – 11,013 •
Columbia – 10,999
2,500 to 10,000 people •
Mascoutah – 8,754 •
Olney – 8,701 •
Harrisburg – 8,219 •
Chester – 7,640 •
Salem – 7,282 •
West Frankfort – 7,275 •
Robinson – 7,150 •
Murphysboro – 7,093 •
Mount Carmel – 7,015 •
Benton – 6,709 •
Metropolis – 5,969 •
Carterville – 5,848 •
Du Quoin – 5,827 •
Pinckneyville – 5,066 •
Fairfield – 4,883 •
Carmi – 4,865 •
Flora – 4,803 •
Lebanon – 4,691 •
Breese – 4,641 •
Freeburg – 4,582 •
Caseyville – 4,400 •
Anna – 4,303 •
Lawrenceville – 4,164 •
Sparta – 4,095 •
Millstadt – 4,071 •
Smithton – 4,006 •
Marshall – 3,947 •
Red Bud – 3,804 •
Eldorado – 3,743 •
Scott AFB – 3,612 •
New Baden – 3,428 •
Johnston City – 3,384 •
Carlyle – 3,253 •
Nashville – 3,105 •
Newton – 2,777 •
Christopher – 2,697 •
Trenton – 2,690 •
McLeansboro – 2,675 •
Sumner – 2,631 Following the 2020 redistricting, this district will go from covering southeastern Illinois to encompassing the entirety of
Southern Illinois, spanning the Illinois-Missouri-Kentucky-Indiana border. It will take in
Monroe,
Randolph,
Clinton,
Perry,
Jackson,
Union,
Alexander,
Pulaski,
Massac,
Johnson,
Williamson,
Jefferson,
Marion,
Clay,
Effingham,
Wayne,
Hamilton,
Saline,
Pope,
Hardin,
Gallatin,
White,
Edwards,
Wabash,
Richland,
Lawrence,
Jasper,
Crawford,
Cumberland, and
Clark Counties, most of
St. Clair County, and half of
Coles County. St. Clair County is split between this district and the
13th district. They are partitioned by a Conrail line, Tanglewood Parkway, Donner Ridge, Hollywood Heights Rd, Oliver St, CSX Transportation Line, S Oak St, W 5th St, S Lincoln Ave, E US Highway 50, County Rd 218, Old O'Fallon Rd, Frank Scott Parkway E, N Green Mount Rd, S Green Mount Rd, Park Rd, S 59th St, Old St. Louis Rd, Illinois Highway 15, Rolling Acres Ln, Excellence Dr, Powdermill Creek, Cemetery Rd, and Illinois Highway 50. The 12th district takes in the municipalities of
Mascoutah,
Lebanon,
New Athens,
Marissa,
Millstadt,
Smithton,
Freeburg,
Summerfield,
Scott AFB,
Rentchler,
Floraville,
Paderborn,
Fayetteville,
St. Libory,
Darmstadt, and
Lenzburg; most of
Shiloh; half of
O'Fallon; and part of
Caseyville,
Fairview Heights, and
Belleville. Coles County is split between this district and the
15th district. They are partitioned by West St, North County Rd 1800 East, Lincoln Prairie Grass Trail, 18th St, County Rd 1600 East, County Rd 400 North, County Rd 1240 East, Illinois Route 16, Dettro Dr, 700 North Rd, Old Fellow Rd, and the Kickapoo Creek. The 12th district takes in the communities of
Ashmore,
Oakland,
Lerna,
Janesville (shared with Cumberland County), and
Trilla; part of southern
Mattoon; and part of
Charleston. == Recent election results from statewide races ==