Illinois’s 12th
U.S. House · 746,831 people
- president 2024 (2024 lines)
- R +43.4
The district
The same lines in 2024 and 2026. First used in 2022.
The district in the page colour, the districts around it in outline (each links to its page), and the counties it takes in by 2020 population.
Congressional District 12
As drawn for 2024; these lines were first used in 2022
In the state
Counties
| County | Of the district | Of the county |
|---|---|---|
| St. Clair County | 12% | 36% |
| Williamson County | 8.9% | 100% |
| Jackson County | 7.0% | 100% |
| Franklin County | 5.0% | 100% |
| Marion County | 5.0% | 100% |
Boundaries: U.S. Census Bureau cartographic boundary files (2025; 2026 lines from TIGER/Line 2026).
Who holds it
Mike Bost (R) holds the seat. 1,137 statements classified this term.
The member’s profile has what they say, how they vote, their ideology and the money they raise.
- Mike BostCSIP 0.85 · 2.5% extreme labelsR
CSIP 0.85: the lab’s ideology score from roll calls, donations and text; 0 is the centre of the scale.
Elections
2026: Mike Bost (R) is projected to win by 39.0 points. Unofficial, about 90% counted.
The 2026 count comes from Candidates in American General Elections (CAGE), entered from NYT and NBC reporting until the results are certified; earlier results from MIT Election Data and Science Lab, only for elections held on these lines. The 2026 race page has the candidates, what they say and their money.
2026
General election
| Candidate | Party | Votes | Share |
|---|---|---|---|
| Mike Bostcalledincumbent | R | 189,443 | 69.5% |
| Julie Fortier | D | 83,281 | 30.5% |
Unofficial: about 90% of the expected vote counted; called by a network. Source: CAGE.
Earlier results
Since 2022
2024 general election
| Candidate | Party | Votes | Share |
|---|---|---|---|
| Mike Bostwon | R | 272,754 | 74.2% |
| Brian Roberts | D | 94,875 | 25.8% |
Certified results. Source: MIT Election Data and Science Lab.
2022 general election
| Candidate | Party | Votes | Share |
|---|---|---|---|
| Mike Bostwon | R | 218,379 | 75.0% |
| Homer Markel | D | 72,791 | 25.0% |
Certified results. Source: MIT Election Data and Science Lab.
How the district voted for president
Shares of all votes cast
| Year, lines | Democratic | Republican | Margin |
|---|---|---|---|
| 2024, 2024 lines | 27.5% | 71.0% | R +43.4 |
| 2024, 2026 lines | 27.5% | 71.0% | R +43.4 |
| 2020, 2024 lines | 27.7% | 70.5% | R +42.8 |
| 2020, 2026 lines | 27.7% | 70.5% | R +42.8 |
Presidential results by district: The Downballot. Shown here with its credit; its terms keep it out of the bulk files and the API.
Who lives there
Who lives in Illinois’s 12th district, beside Illinois.
From the Census Bureau’s American Community Survey; ± is the 90 percent margin of error.
The district at a glance
Congressional District 12 (119th Congress): the district as drawn for 2024
People
±1,762 (an estimate)
Median age
±0.2 · Illinois 39.0
Median household income
±$976 · Illinois $83,390
Race and ethnicity
Share of everyone; Hispanic or Latino people may be of any race, the other groups are not Hispanic
District
Illinois
Show the data
| Part | District | Illinois |
|---|---|---|
| White | 87.2% | 58.1% |
| Black | 4.8% | 13.3% |
| Hispanic or Latino | 3.1% | 18.8% |
| Asian | 1.0% | 5.9% |
| Another race or more than one | 3.9% | 3.9% |
Age, schooling, income and place
District over Illinois; ± is the 90 percent margin of error
Show the data
| Row | District | Illinois |
|---|---|---|
| Aged 65 and over | 19.9% | 17.0% |
| Bachelor’s degree or more (adults 25+) | 24.4% | 37.9% |
| Below the poverty line | 13.1% | 11.8% |
| Born outside the U.S. | 2.0% | 14.8% |
| Veterans (adults) | 8.6% | 4.8% |
| Living in rural areas (2020 Census) | 60.4% | 13.1% |
Source: ACS 2020–2024 5-year estimates (Census Bureau); rural share from the 2020 Census.
About these figures
The figures from the American Community Survey are estimates from a sample, not a count. The ± beside each is its 90 percent margin of error: nine times in ten the true value lies within that range. In small districts the margins are wide, so a gap of a few points from Illinois may be noise. Shares are of everyone in the district, except education (adults 25 and over), poverty (people whose poverty status is known) and veterans (civilian adults).
These are the Census Bureau’s own estimates for the district; margins on shares are approximated from the counts’ margins.
The rural share counts the people living outside the urban areas the Census Bureau drew from the 2020 Census; it is a count, with no margin of error.
Threats
No federal prosecution for threatening the district’s member has been announced.
Prosecutions the Justice Department announced in a press release, tied to the member by name and office: not every threat. See Political Violence.
Files and sources
Everything here is in the House districts file and the data API.
The House districts file has one row per district and map with its boundaries; the API serves this district at /v1/districts/IL/cd/12. Sources: the Census Bureau and Geocorr (people, boundaries, counties), CAGE and MIT Election Data and Science Lab (results), the Justice Department (threats), The Downballot (the presidential vote, on this page only). Credits and terms are on Open data.