- Lead
- 310
- Total
- 94,609
- vs nation
- D+1.8
Illinois 40th State Senate District
President margin by year
Place winner margin
President results by year
Modeled candidate-vote estimate on current district boundaries
- Lead
- 7,065
- Total
- 100,153
- vs nation
- D+2.6
- Lead
- 8,873
- Total
- 93,048
- vs nation
- D+7.4
- Lead
- 10,155
- Total
- 87,074
- vs nation
- D+7.8
- Lead
- 16,906
- Total
- 90,842
- vs nation
- D+11.3
- Lead
- 3,368
- Total
- 83,872
- vs nation
- D+6.5
- Lead
- 6,821
- Total
- 70,505
- vs nation
- D+9.2
- Lead
- 10,203
- Total
- 60,470
- vs nation
- D+8.4
Key facts
- 2024 presidential margin
- D+0.3MIT Election Lab
- Population
- 217,3182024 5-year
- Population density
- 310 / sq mi2024 5-year · TIGER/Line
- Land area
- 702 sq miTIGER/Line
- Median household income
- $75,2712024 5-year
- White (non-Hispanic)
- 54.9%2024 5-year
- Black
- 25.9%2024 5-year
- Hispanic / Latino
- 14.3%2024 5-year
- Peak Democratic margin
- D+22.7 in 1964MIT Election Lab
- Peak Republican margin
- R+55.3 in 1920MIT Election Lab
- Most similar
- State Senate District 18, IL · twin score 82.4
presidential history
Party record book
Illinois 40th 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
Lyndon B. Johnson1964
61.3%
38,040 votes · D+22.7 · modeled estimate
Runner-up · Franklin D. Roosevelt, 1936 · 59.0%
Republican
Warren G. Harding1920
76.2%
17,093 votes · R+55.3 · modeled estimate
Runner-up · Theodore Roosevelt, 1904 · 69.4%
Most votes
Largest number of votes cast for the party’s presidential nominee here.
Democratic
Barack Obama2008
53,378votes
58.8% of the vote · D+18.6 · modeled estimate
Runner-up · Joe Biden, 2020 · 52,641 votes
Republican
Donald Trump2024
46,213votes
48.8% of the vote · D+0.3 · modeled estimate
Runner-up · Donald Trump, 2020 · 45,576 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
Al Smith1928
+15.1pts D vs U.S.
Place R+2.4 · U.S. R+17.5 · modeled estimate
Runner-up · Barack Obama, 2008 · +11.3 pts
Republican
Warren G. Harding1920
+29.1pts R vs U.S.
Place R+55.3 · U.S. R+26.2 · modeled estimate
Runner-up · Theodore Roosevelt, 1904 · +24.9 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 | 53.2%49,540 | 46.8%43,539 | 93,079 |
| 2020 | R | 49.5%38,847 | 50.5%39,668 | 78,515 |
Illinois 40th State Senate District sits in the Upper Midwest. In 2024 it voted Democratic.
Across the recorded series it reached a Democratic high of 22.7 points in 1964 and a Republican high of 55.3 points in 1920. Between 2020 and 2024 the district moved 6.7 points toward the Republican candidate; the 2024 margin was 0.3 points.
A population of 217,318, a 55% non-Hispanic-white share, and a median household income of $75,271 describe the district. The district's voting pattern over the last decade is most similar to that of State Senate District 18 and State Senate District 43.
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.
District research tools
Open the source-auditable district brief for electoral baseline, electorate, current-cycle coverage, geography, official dates, and methodology. Open campaign intelligence report → · Browse all comparisons →
Illinois 40th State Senate District. Akashic. https://akashic.app/sld-upper/17040/. Accessed May 20, 2026. License: CC BY 4.0.