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Illinois's 12th congressional district
Interactive map of district boundaries since January 3, 2023
Representative	Mike Bost R–Murphysboro
Area	14,296.2 sq mi (37,027 km2)
Distribution	75.4% urban 24.6% rural
Population (2024)	745,901
Median household income	$70,903[1]
Ethnicity	86.9%White 4.9%Black 3.9%Two or more races 2.8%Hispanic 1.0%Asian 0.5% other
Cook PVI	R+22[2]

The12th congressional district ofIllinois is acongressional district in the southern part ofU.S. state ofIllinois. It has been represented by RepublicanMike Bost since 2015. With aCook Partisan Voting Index of R+22, it is the most Republican district in Illinois.^[2]

The district covers parts ofMadison andSt. Clair counties, and all ofAlexander,Franklin,Hamilton,Jackson,Jefferson,Monroe,Perry,Pulaski,Randolph,Union andWilliamson counties, as of the 2011 redistricting which followed the2010 census. All or parts ofBelleville,Cahokia,Carbondale,Collinsville,East St. Louis,Granite City,Herrin,Marion,Mt. Vernon,O'Fallon,Shiloh andSwansea are included.^[3] The representatives for these districts were elected in the 2012 primary and general elections, and the boundaries became effective on January 5, 2013.

• 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

• 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 ofSouthern Illinois, spanning the Illinois-Missouri-Kentucky-Indiana border. It will take inMonroe,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, andClark Counties, most ofSt. Clair County, and half ofColes County.

St. Clair County is split between this district and the13th 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 ofMascoutah,Lebanon,New Athens,Marissa,Millstadt,Smithton,Freeburg,Summerfield,Scott AFB,Rentchler,Floraville,Paderborn,Fayetteville,St. Libory,Darmstadt, andLenzburg; most ofShiloh; half ofO'Fallon; and part ofCaseyville,Fairview Heights, andBelleville.

Coles County is split between this district and the15th 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 ofAshmore,Oakland,Lerna,Janesville (shared with Cumberland County), andTrilla; part of southernMattoon; and part ofCharleston.

Name	Party	Years	Cong– ress	Electoral history	Counties
District created March 4, 1863
William Ralls Morrison (Waterloo)	Democratic	March 4, 1863 – March 3, 1865	38th	Elected in 1862. Lost re-election.	1863–1873 Clinton,Madison,Monroe,Randolph,St. Clair, andWashington
Jehu Baker (Belleville)	Republican	March 4, 1865 – March 3, 1869	39th 40th	Elected in 1864. Re-elected in 1866. Retired.
John B. Hay (Belleville)	Republican	March 4, 1869 – March 3, 1873	41st 42nd	Elected in 1868. Re-elected in 1870. Redistricted to the17th district and lost re-election.
James Carroll Robinson (Springfield)	Democratic	March 4, 1873 – March 3, 1875	43rd	Redistricted from the8th district andre-elected in 1872. Retired.	1873–1883 Cass,Christian,Menard,Morgan,Sangamon, andScott
William McKendree Springer (Springfield)	Democratic	March 4, 1875 – March 3, 1883	44th 45th 46th 47th	Elected in 1874. Re-elected in 1876. Re-elected in 1878. Re-elected in 1880. Redistricted to the13th district.
James M. Riggs (Winchester)	Democratic	March 4, 1883 – March 3, 1887	48th 49th	Elected in 1882. Re-elected in 1884. Retired.	1883–1895 [data missing]
George A. Anderson (Quincy)	Democratic	March 4, 1887 – March 3, 1889	50th	Elected in 1886. Retired.
Scott Wike (Pittsfield)	Democratic	March 4, 1889 – March 3, 1893	51st 52nd	Elected in 1888. Re-elected in 1890. Lost renomination.
John James McDannold (Mount Sterling)	Democratic	March 4, 1893– March 3, 1895	53rd	Elected in 1892. Retired.
Joseph Gurney Cannon (Danville)	Republican	March 4, 1895– March 3, 1903	54th 55th 56th 57th	Redistricted from the15th district andre-elected in 1894. Re-elected in 1896. Re-elected in 1898. Re-elected in 1900. Redistricted to the18th district.	1895–1903 Iroquois,Kankakee,Vermillion, andWill
Charles Eugene Fuller (Belvidere)	Republican	March 4, 1903– March 3, 1913	58th 59th 60th 61st 62nd	Elected in 1902. Re-elected in 1904. Re-elected in 1906. Re-elected in 1908. Re-elected in 1910. Lost re-election.	1903–1913 Boone,DeKalb,Grundy,Kendall,LaSalle, andWinnebago
William H. Hinebaugh (Ottawa)	Progressive	March 4, 1913– March 3, 1915	63rd	Elected in 1912. Lost re-election.	1913–1949 Boone,DeKalb,Grundy,Kendall,LaSalle, andWinnebago
Charles Eugene Fuller (Belvidere)	Republican	March 4, 1915– June 25, 1926	64th 65th 66th 67th 68th 69th	Elected again in 1914. Re-elected in 1916. Re-elected in 1918. Re-elected in 1920. Re-elected in 1922. Re-elected in 1924. Died.
Vacant		June 25, 1926– March 3, 1927	69th
John T. Buckbee (Rockford)	Republican	March 4, 1927– April 23, 1936	70th 71st 72nd 73rd 74th	Elected in 1926. Re-elected in 1928. Re-elected in 1930. Re-elected in 1932. Re-elected in 1934. Died.
Vacant		April 23, 1936– January 3, 1937	74th
Noah M. Mason (Oglesby)	Republican	January 3, 1937– January 3, 1949	75th 76th 77th 78th 79th 80th	Elected in 1936. Re-elected in 1938. Re-elected in 1940. Re-elected in 1942. Re-elected in 1944. Re-elected in 1946. Redistricted to the15th district.
Edgar A. Jonas (Chicago)	Republican	January 3, 1949– January 3, 1955	81st 82nd 83rd	Elected in 1948. Re-elected in 1950. Re-elected in 1952. Lost re-election.	1949–1953 Cook
					1953–1963 Cook
Charles A. Boyle (Chicago)	Democratic	January 3, 1955– November 4, 1959	84th 85th 86th	Elected in 1954. Re-elected in 1956. Re-elected in 1958. Died.
Vacant		November 4, 1959– January 3, 1961	86th
Edward Rowan Finnegan (Chicago)	Democratic	January 3, 1961– January 3, 1963	87th	Elected in 1960. Redistricted to the9th district.
Robert McClory (Lake Bluff)	Republican	January 3, 1963– January 3, 1973	88th 89th 90th 91st 92nd	Elected in 1962. Re-elected in 1964. Re-elected in 1966. Re-elected in 1968. Re-elected in 1970. Redistricted to the13th district.	1963–1967 Boone,Lake, andMcHenry
					1967–1973 Cook,Lake, andMcHenry
Phil Crane (McHenry)	Republican	January 3, 1973– January 3, 1993	93rd 94th 95th 96th 97th 98th 99th 100th 101st 102nd	Elected in 1972. Re-elected in 1974. Re-elected in 1976. Re-elected in 1978. Re-elected in 1980. Re-elected in 1982. Re-elected in 1984. Re-elected in 1986. Re-elected in 1988. Re-elected in 1990. Redistricted to the8th district.	1973–1983 Cook andLake
					1983–1993 Cook,Lake, andMcHenry
Jerry Costello (Belleville)	Democratic	January 3, 1993– January 3, 2013	103rd 104th 105th 106th 107th 108th 109th 110th 111th 112th	Redistricted from the21st district andre-elected in 1992. Re-elected in 1994. Re-elected in 1996. Re-elected in 1998. Re-elected in 2000. Re-elected in 2002. Re-elected in 2004. Re-elected in 2006. Re-elected in 2008. Re-elected in 2010. Retired.	1993–2003 Alexander,Jackson,Madison,Monroe,Perry,Randolph,St. Clair,Union, andWilliamson
					2003–2013 Alexander,Franklin,Jackson,Madison,Monroe,Perry,Pulaski,Randolph,St. Clair,Union,Williamson
William Enyart (Belleville)	Democratic	January 3, 2013– January 3, 2015	113th	Elected in 2012. Lost re-election.	2013–2023 Alexander,Franklin,Jackson,Jefferson,Madison,Monroe,Perry,Pulaski,Randolph,St. Clair,Union, andWilliamson
Mike Bost (Murphysboro)	Republican	January 3, 2015– present	114th 115th 116th 117th 118th 119th	Elected in 2014. Re-elected in 2016. Re-elected in 2018. Re-elected in 2020. Re-elected in 2022. Re-elected in 2024.
					2023–present Alexander,Clark,Clay,Clinton,Coles (part),Crawford,Cumberland,Edwards,Effingham,Franklin,Gallatin,Hamilton,Hardin,Jackson,Jasper,Jefferson,Johnson,Lawrence,Marion,Massac,Monroe,Perry,Pope,Pulaski,Randolph,Richland,Saline,St. Clair (part),Union,Wabash,Washington,Wayne,White, andWilliamson

This sectionneeds expansion. You can help byadding to it.(March 2015)

• Illinois's congressional districts
• List of United States congressional districts

• Martis, Kenneth C. (1989).The Historical Atlas of Political Parties in the United States Congress. New York: Macmillan Publishing Company.
• Martis, Kenneth C. (1982).The Historical Atlas of United States Congressional Districts. New York: Macmillan Publishing Company.
• Congressional Biographical Directory of the United States 1774–present, bioguide.congress.gov; accessed November 10, 2016.

• Washington Post page on the 12th District of Illinois
• U.S. Census Bureau - 5th District Fact SheetArchived September 28, 2011, at theWayback Machine

38°00′N89°15′W / 38.000°N 89.250°W /38.000; -89.250

• Congressional districts of Illinois
• Alexander County, Illinois
• Constituencies established in 1863
• 1863 establishments in Illinois

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