St. Clair County, Illinois: Industrial Catholic Metro county. In 2024, voted D+8%. Democratic peak: D+45 in 1964.
Key facts
- 2024 presidential margin
- D+8MIT Election Lab
- Political typology
- Industrial Catholic MetroAkashic typology
- Population
- 253,6942024 5-year
- Median household income
- $73,8542024 5-year
- White (non-Hispanic)
- 60.1%2024 5-year
- Black
- 27.9%2024 5-year
- Hispanic / Latino
- 5.1%2024 5-year
- Peak Democratic margin
- D+45 in 1964MIT Election Lab
- Peak Republican margin
- R+18 in 1920MIT Election Lab
- Most similar
- Marquette County, MI · similarity 0.99
2024 results by precinct
2024 precinct map of St. Clair CountyPrecinct-level 2024 presidential results for St. Clair County, with each precinct boundary colored by Democratic-vs-Republican margin.
—
Margin—
Turnout—
Harris +50Trump +50
Real precinct boundaries. Hover for vote totals.
presidential history
Presidential margin, 1876–2024
Democratic minus Republican, by election
| Year | Margin (D minus R) |
|---|---|
| 1876 | No data |
| 1880 | No data |
| 1884 | No data |
| 1888 | No data |
| 1892 | +6.6% |
| 1896 | −3.5% |
| 1900 | +0.3% |
| 1904 | −17.3% |
| 1908 | −4.9% |
| 1912 | +10.3% |
| 1916 | +1.1% |
| 1920 | −18.1% |
| 1924 | −16.6% |
| 1928 | +7.9% |
| 1932 | +33.8% |
| 1936 | +32.9% |
| 1940 | +19.5% |
| 1944 | +18.0% |
| 1948 | +27.3% |
| 1952 | +20.5% |
| 1956 | +14.2% |
| 1960 | +23.1% |
| 1964 | +44.8% |
| 1968 | +16.1% |
| 1972 | −4.0% |
| 1976 | +18.6% |
| 1980 | +4.0% |
| 1984 | +1.2% |
| 1988 | +14.4% |
| 1992 | +23.9% |
| 1996 | +21.5% |
| 2000 | +13.6% |
| 2004 | +10.8% |
| 2008 | +22.4% |
| 2012 | +14.3% |
| 2016 | +5.7% |
| 2020 | +8.6% |
| 2024 | +7.8% |
DemocraticRepublican
38 presidential elections
| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| D | 63,433 | 54,021 | 119,962 | ||
| D | 68,325 | 57,150 | 129,405 | ||
| D | 60,756 | 53,857 | 121,436 | ||
| D | 67,285 | 50,125 | 119,827 | ||
| D | 76,160 | 47,958 | 125,744 | ||
| D | 62,410 | 50,203 | 113,189 | ||
| D | 55,961 | 42,299 | 100,393 | ||
| D | 53,405 | 33,066 | 94,429 | ||
| D | 57,625 | 31,951 | 107,541 | ||
| D | 55,465 | 41,439 | 97,313 | ||
| D | 52,294 | 51,046 | 104,148 | ||
| D | 50,046 | 46,063 | 100,673 | ||
| D | 59,177 | 40,333 | 101,065 | ||
| R | 46,636 | 50,519 | 98,097 | ||
| D | 50,726 | 34,442 | 100,874 | ||
| D | 74,005 | 28,226 | 102,231 | ||
| D | 67,367 | 42,046 | 109,751 | ||
| D | 55,295 | 41,528 | 97,106 | ||
| D | 60,311 | 39,713 | 100,503 | ||
| D | 54,260 | 30,883 | 85,617 | ||
| D | 48,325 | 33,557 | 82,209 | ||
| D | 53,482 | 35,998 | 89,891 | ||
| D | 54,238 | 26,684 | 83,762 | ||
| D | 47,305 | 22,744 | 72,571 | ||
| D | 36,374 | 31,026 | 68,037 | ||
| R | 14,921 | 23,380 | 50,994 | ||
| R | 14,032 | 21,681 | 42,231 | ||
| D | 22,622 | 22,134 | 46,331 | ||
| D | 10,826 | 8,156 | 25,866 | ||
| R | 11,342 | 12,619 | 25,934 | ||
| R | 8,200 | 11,926 | 21,561 | ||
| D | 9,827 | 9,764 | 20,063 | ||
| R | 8,345 | 8,960 | 17,583 | ||
| D | 7,207 | 6,276 | 14,034 | ||
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Demographics
2024 ACS
Race, ethnicity, and ancestry
Click any group to see the ancestries typically reported within it.
German
21.5%
Irish
9.7%
English
8.7%
American
4.2%
Italian
2.8%
Polish
2.6%
French
2.6%
African American
22.3%
Multiple ancestry combinations reported; no single grouping above 1%.
American Indian, Alaska Native, Native Hawaiian, and Pacific Islander combined.
Source · American Community Survey 5-year estimates, 2024 release. Hispanic/Latino is an ethnicity that overlaps the race categories, so these shares can total more than 100%. Ancestry is a self-reported, multiple-response item; ancestry percentages do not sum to the parent race percentage.
2024 ACS
Age distribution by sex
Median age: 39.9 in this county, 39.1 nationally
Male
Age
Female
85+
75–84
65–74
55–64
45–54
35–44
25–34
18–24
5–17
<5
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Median household income
Inflation-adjusted dollars
$73,854
St. Clair County ranks near the middle of US counties.
St. Clair County$73,854
Illinois$83,390
United States$80,734
St. Clair County ranks near the middle of US counties by median household income.
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Poverty rate
All persons below federal poverty line
13.6%
Children face moderate poverty.
Children under 1818.9%
Working age (18–64)11.9%
Seniors (65+)12.8%
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Language at home
Population aged 5 and older
95.0%
speak English only
Spanish2.8%
Asian & Pacific Islander1.0%
Other Indo-European0.9%
Other languages0.3%
Source · ACS 5-year estimates, 2024.
2020 religion census
Religious adherents
Adherents per capita by tradition
Source · 2020 US Religion Census. Remaining 53.6% of residents not counted as adherents by any reporting body.
St. Clair County anchors Illinois's Metro East region across the Mississippi from St. Louis, with a diverse population and urban-suburban mix that has returned Democratic presidential margins in the single to low double digits for over two decades.
Its margins are typically close. The Democratic margin reached forty-five points in 1964; the Republican margin reached eighteen points in 1920. Between 2020 and 2024 the county moved one point toward the Republican candidate; the 2024 margin was eight points.
Its demographics sit near national norms: a 60% non-Hispanic-white share, a median household income of $73,854, and a 14% poverty rate. The county's voting pattern over the last decade is most similar to that of Marquette County and Rock Island County.
Most similar counties
Compare two places, side by side
Twelve curated comparisons line up election history, demographics, and the divergence story for two places at a glance. Browse all comparisons →
Cite this page
All citations released under CC BY 4.0. Attribution: Akashic Intelligence.
St. Clair County, Illinois. Akashic. https://akashic.app/county/17163/. Accessed May 20, 2026. License: CC BY 4.0.
License: CC BY 4.0
More industrial catholic metro counties
Frequently asked questions
How did St. Clair County, Illinois vote in 2024?
In 2024, St. Clair County, Illinois voted Democratic by 7.8 points (D+8), carried by the Democratic candidate. Out of 119,962 votes cast, 63,433 went Democratic and 54,021 went Republican.
What is St. Clair County, Illinois's political typology?
Akashic places St. Clair County, Illinois in the "Industrial Catholic Metro" typology — Mid-size industrial metros with Catholic ethnic roots — among the most competitive, swing-prone ground in the country. The typology is a data-driven cluster built from vote share, vote swing, race and ethnicity, income, language spoken at home, religion, and ancestry. Across 38 elections in the dataset, the county has voted Democratic 28 times, Republican 6 times, and other 0 times.
When did St. Clair County, Illinois last vote Republican?
The most recent presidential election in which St. Clair County, Illinois voted Republican was 1972.
How many people live in St. Clair County, Illinois?
St. Clair County, Illinois has a population of 253,694 according to the 2024 American Community Survey 5-year estimates from the US Census Bureau.
What is the median household income in St. Clair County, Illinois?
Median household income in St. Clair County, Illinois is $73,854 — below the national median of $80,734. The Illinois state median is $83,390.
What is the political history of St. Clair County, Illinois?
Akashic tracks 38 presidential elections in St. Clair County, Illinois from 1876 to 2024. Of those, 28 went Democratic and 6 went Republican. The county's typology — "Industrial Catholic Metro" — captures where that record, its demographics, and its recent swing place it among American communities.