- Lead
- 16,760
- Total
- 92,110
- vs nation
- D+19.7
Illinois 31st State Senate District
President margin by year
Place winner margin
President results by year
Modeled candidate-vote estimate on current district boundaries
- Lead
- 22,846
- Total
- 101,248
- vs nation
- D+18.1
- Lead
- 15,300
- Total
- 91,336
- vs nation
- D+14.7
- Lead
- 3,977
- Total
- 86,797
- vs nation
- D+0.7
- Lead
- 14,326
- Total
- 90,237
- vs nation
- D+8.6
- Lead
- 4,549
- Total
- 83,312
- vs nation
- R+3.0
- Lead
- 4,507
- Total
- 73,128
- vs nation
- R+6.7
- Lead
- 2,095
- Total
- 62,380
- vs nation
- R+11.9
Key facts
- 2024 presidential margin
- D+18.2MIT Election Lab
- Population
- 217,2172024 5-year
- Population density
- 1,537 / sq mi2024 5-year · TIGER/Line
- Land area
- 141 sq miTIGER/Line
- Median household income
- $102,2032024 5-year
- White (non-Hispanic)
- 52.2%2024 5-year
- Black
- 8.3%2024 5-year
- Hispanic / Latino
- 28.6%2024 5-year
- Peak Democratic margin
- D+22.6 in 2020MIT Election Lab
- Peak Republican margin
- R+72.3 in 1920MIT Election Lab
- Most similar
- State Senate District 42, IL · twin score 95.4
presidential history
Party record book
Illinois 31st State Senate District · the strongest Democratic and Republican presidential performances recorded here, measured three ways.
1892–2024 (partial returns from 1876) · 38 presidential cycles · 38 with a vote-share denominator · 34 with a national benchmark
Highest vote share
Largest share of the presidential candidate vote cast here.
Democratic
Joe Biden2020
59.9%
60,637 votes · D+22.6 · modeled estimate
Runner-up · Kamala Harris, 2024 · 58.0%
Republican
Warren G. Harding1920
82.9%
4,957 votes · R+72.3 · modeled estimate
Runner-up · Theodore Roosevelt, 1904 · 79.9%
Most votes
Largest number of votes cast for the party’s presidential nominee here.
Democratic
Joe Biden2020
60,637votes
59.9% of the vote · D+22.6 · modeled estimate
Runner-up · Kamala Harris, 2024 · 53,437 votes
Republican
George W. Bush2004
43,629votes
52.4% of the vote · R+5.5 · modeled estimate
Runner-up · Mitt Romney, 2012 · 40,702 votes
Best relative to the U.S.
This Place’s margin against the national margin in the same election — positive when it leaned toward the party more than the country did.
Democratic
Kamala Harris2024
+19.7pts D vs U.S.
Place D+18.2 · U.S. R+1.5 · modeled estimate
Runner-up · Joe Biden, 2020 · +18.1 pts
Republican
William McKinley1896
+47.6pts R vs U.S.
Place R+53.7 · U.S. R+6.1 · modeled estimate
Runner-up · Warren G. Harding, 1920 · +46.1 pts
Current officeholders
State legislative officeholder from OpenStates nightly current-legislator data.
Senate and governor results are in the Office selector at the top of this page.
U.S. House
Each row is a county-allocated estimate of U.S. House votes for this district — county returns apportioned onto its boundary, not precinct-counted. “Vote lead” is the estimated local lead here, not necessarily the winner of the full contest.
| Year | Vote lead | Democratic | Republican | Total |
|---|---|---|---|---|
| 2024 | D | 59.2%55,347 | 40.8%38,191 | 93,538 |
| 2020 | D | 60.1%60,282 | 39.9%39,985 | 100,267 |
Illinois 31st State Senate District sits in the Upper Midwest. In 2024 it voted Democratic.
Across the recorded series it reached a Democratic high of 22.6 points in 2020 and a Republican high of 72.3 points in 1920. Between 2020 and 2024 the district moved 4.4 points toward the Republican candidate; the 2024 margin was 18.2 points.
A population of 217,217, a 52% non-Hispanic-white share, and a median household income of $102,203 describe the district. The district's voting pattern over the last decade is most similar to that of State Senate District 42 and State Senate District 25.
The state-senate districts whose fingerprint — 2000–2024 trajectory, demographics, ancestry, religion — sits closest to this one, and why.
Twin score (0–100) = weighted cosine between tier-standardized fingerprints: presidential margins 2000–2024 with 12-yr trend and elasticity, ACS income, age, education, population and race, top reported ancestries, and religious adherence — chips name the closest-shared dimensions and the widest gap. Re-weight the groups in the twins explorer.
Compare State Senate District 31 with…
- Los Angeles County, CAThe two largest Democratic-anchor counties in America.
- New York County, NYCook vs Manhattan — Midwest blue vs East-coast bluest.
- Harris County, TXCook vs Harris — Midwest blue vs Sun Belt swing.
Open campaign intelligence report → · All twelve comparisons →
Illinois 31st State Senate District. Akashic. https://akashic.app/sld-upper/17031/. Accessed May 20, 2026. License: CC BY 4.0.