Mercer County, Illinois: Heartland Swing county. In 2024, voted R+27%. Republican peak: R+53 in 1920.
Key facts
- 2024 presidential margin
- R+27MIT Election Lab
- Political typology
- Heartland SwingAkashic typology
- Population
- 15,4952024 5-year
- Median household income
- $74,1822024 5-year
- White (non-Hispanic)
- 94.2%2024 5-year
- Black
- 0.6%2024 5-year
- Hispanic / Latino
- 3.4%2024 5-year
- Peak Democratic margin
- D+20 in 1996MIT Election Lab
- Peak Republican margin
- R+53 in 1920MIT Election Lab
- Most similar
- Adams County, WI · similarity 0.99
2024 results by precinct
2024 precinct map of Mercer CountyPrecinct-level 2024 presidential results for Mercer 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 | −10.6% |
| 1896 | −14.3% |
| 1900 | −21.5% |
| 1904 | −36.3% |
| 1908 | −21.9% |
| 1912 | +12.9% |
| 1916 | −20.9% |
| 1920 | −53.4% |
| 1924 | −47.6% |
| 1928 | −41.9% |
| 1932 | −1.4% |
| 1936 | −2.8% |
| 1940 | −24.6% |
| 1944 | −26.6% |
| 1948 | −25.5% |
| 1952 | −41.1% |
| 1956 | −31.7% |
| 1960 | −23.2% |
| 1964 | +2.2% |
| 1968 | −19.8% |
| 1972 | −22.1% |
| 1976 | −8.1% |
| 1980 | −19.5% |
| 1984 | −10.4% |
| 1988 | +6.6% |
| 1992 | +11.8% |
| 1996 | +20.1% |
| 2000 | +8.6% |
| 2004 | +1.2% |
| 2008 | +11.9% |
| 2012 | +7.4% |
| 2016 | −20.4% |
| 2020 | −24.0% |
| 2024 | −27.1% |
DemocraticRepublican
38 presidential elections
| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| R | 2,950 | 5,215 | 8,346 | ||
| R | 3,280 | 5,418 | 8,914 | ||
| R | 3,071 | 4,807 | 8,525 | ||
| D | 4,507 | 3,876 | 8,568 | ||
| D | 4,887 | 3,833 | 8,848 | ||
| D | 4,512 | 4,405 | 8,974 | ||
| D | 4,400 | 3,688 | 8,318 | ||
| D | 4,278 | 2,688 | 7,897 | ||
| D | 3,990 | 2,983 | 8,540 | ||
| D | 4,204 | 3,683 | 7,929 | ||
| R | 3,982 | 4,907 | 8,927 | ||
| R | 3,361 | 5,144 | 9,156 | ||
| R | 4,090 | 4,816 | 8,982 | ||
| R | 3,477 | 5,452 | 8,940 | ||
| R | 3,143 | 4,844 | 8,600 | ||
| D | 4,410 | 4,220 | 8,630 | ||
| R | 3,476 | 5,582 | 9,061 | ||
| R | 2,969 | 5,732 | 8,708 | ||
| R | 2,679 | 6,416 | 9,097 | ||
| R | 3,117 | 5,267 | 8,420 | ||
| R | 3,277 | 5,667 | 8,978 | ||
| R | 3,830 | 6,336 | 10,204 | ||
| R | 4,751 | 5,028 | 9,884 | ||
| R | 4,309 | 4,436 | 8,835 | ||
| R | 2,316 | 5,699 | 8,073 | ||
| R | 1,699 | 5,618 | 8,225 | ||
| R | 1,574 | 5,531 | 7,416 | ||
| R | 3,430 | 5,308 | 9,006 | ||
| O | 1,602 | 959 | 4,996 | ||
| R | 1,777 | 2,871 | 4,992 | ||
| R | 1,386 | 3,230 | 5,075 | ||
| R | 2,110 | 3,304 | 5,563 | ||
| R | 2,329 | 3,120 | 5,524 | ||
| R | 1,975 | 2,470 | 4,687 | ||
| — | — | — | — | ||
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Demographics
2024 ACS
Race, ethnicity, and ancestry
Click any group to see the ancestries typically reported within it.
German
20.8%
Irish
12.2%
English
11.5%
American
5.8%
French
1.9%
Italian
1.5%
Scottish
1.0%
Sample size too small to break out by ancestry reliably.
Multiple ancestry combinations reported; no single grouping above 1%.
Sample size too small to break out by ancestry reliably.
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: 44.7 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
$74,182
Mercer County ranks near the middle of US counties.
Mercer County$74,182
Illinois$83,390
United States$80,734
Mercer 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
8.9%
Child poverty is below the national average.
Children under 1812.2%
Working age (18–64)8.2%
Seniors (65+)6.7%
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Language at home
Population aged 5 and older
97.2%
speak English only
Spanish2.1%
Other Indo-European0.3%
Asian & Pacific Islander0.3%
Other languages0.1%
Source · ACS 5-year estimates, 2024.
2020 religion census
Religious adherents
Adherents per capita by tradition
Source · 2020 US Religion Census. Remaining 63.4% of residents not counted as adherents by any reporting body.
Mercer County's 2024 presidential margin of R+27.1 reflects a broader rural realignment across western Illinois, where small agricultural communities have moved decisively away from their mid-20th-century Democratic leanings.
The Democratic margin here peaked at twenty points in 1996. Between 2020 and 2024 the county moved three points toward the Republican candidate; the 2024 margin was twenty-seven points.
A population of 15,495, a 94% non-Hispanic-white share, and a median household income of $74,182 describe the county. The county's voting pattern over the last decade is most similar to that of Adams County and Henderson 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.
Mercer County, Illinois. Akashic. https://akashic.app/county/17131/. Accessed May 20, 2026. License: CC BY 4.0.
License: CC BY 4.0
More heartland swing counties
Frequently asked questions
How did Mercer County, Illinois vote in 2024?
In 2024, Mercer County, Illinois voted Republican by 27.1 points (R+27), carried by the Republican candidate. Out of 8,346 votes cast, 2,950 went Democratic and 5,215 went Republican.
What is Mercer County, Illinois's political typology?
Akashic places Mercer County, Illinois in the "Heartland Swing" typology — Industrial Midwest swing counties drifting steadily toward the Republican Party. 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 8 times, Republican 25 times, and other 1 times.
When did Mercer County, Illinois last vote Democratic?
The most recent presidential election in which Mercer County, Illinois voted Democratic was 2012.
How many people live in Mercer County, Illinois?
Mercer County, Illinois has a population of 15,495 according to the 2024 American Community Survey 5-year estimates from the US Census Bureau.
What is the median household income in Mercer County, Illinois?
Median household income in Mercer County, Illinois is $74,182 — below the national median of $80,734. The Illinois state median is $83,390.
What is the political history of Mercer County, Illinois?
Akashic tracks 38 presidential elections in Mercer County, Illinois from 1876 to 2024. Of those, 8 went Democratic and 25 went Republican. The county's typology — "Heartland Swing" — captures where that record, its demographics, and its recent swing place it among American communities.