- Lead
- 4,334
- Total
- 34,333
- vs nation
- D+14.1
Iowa 40th State Senate District
President margin by year
Place winner margin
President results by year
Modeled candidate-vote estimate on current district boundaries
- Lead
- 5,536
- Total
- 35,854
- vs nation
- D+11.0
- Lead
- 3,340
- Total
- 34,179
- vs nation
- D+7.7
- Lead
- 6,398
- Total
- 34,391
- vs nation
- D+14.7
- Lead
- 7,428
- Total
- 32,950
- vs nation
- D+15.3
- Lead
- 3,479
- Total
- 32,201
- vs nation
- D+13.3
- Lead
- 2,690
- Total
- 26,726
- vs nation
- D+9.5
- Lead
- 4,420
- Total
- 23,981
- vs nation
- D+9.9
Key facts
- 2024 presidential margin
- D+12.6MIT Election Lab
- Population
- 64,1452024 5-year
- Population density
- 1,986 / sq mi2024 5-year · TIGER/Line
- Land area
- 32.3 sq miTIGER/Line
- Median household income
- $75,9312024 5-year
- White (non-Hispanic)
- 79.9%2024 5-year
- Black
- 8.2%2024 5-year
- Hispanic / Latino
- 3.9%2024 5-year
- Peak Democratic margin
- D+30.0 in 1964MIT Election Lab
- Peak Republican margin
- R+47.1 in 1924MIT Election Lab
- Most similar
- State Senate District 37, IA · twin score 90.3
presidential history
Party record book
Iowa 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
64.9%
11,717 votes · D+30.0 · modeled estimate
Runner-up · Barack Obama, 2008 · 60.5%
Republican
Warren G. Harding1920
71.5%
5,791 votes · R+46.3 · modeled estimate
Runner-up · Herbert Hoover, 1928 · 67.9%
Most votes
Largest number of votes cast for the party’s presidential nominee here.
Democratic
Joe Biden2020
20,226votes
56.4% of the vote · D+15.4 · modeled estimate
Runner-up · Barack Obama, 2012 · 20,030 votes
Republican
Donald Trump2020
14,690votes
41.0% of the vote · D+15.4 · modeled estimate
Runner-up · Donald Trump, 2024 · 14,636 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
Michael Dukakis1988
+21.4pts D vs U.S.
Place D+13.7 · U.S. R+7.7 · modeled estimate
Runner-up · George McGovern, 1972 · +16.5 pts
Republican
Calvin Coolidge1924
+21.9pts R vs U.S.
Place R+47.1 · U.S. R+25.2 · modeled estimate
Runner-up · Alf Landon, 1936 · +21.7 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.
Its Democratic presidential margin was D+12.7 in 2024 and D+22.5 in 2008. The district had about 10,500 residents, 83.6% White alone in the 2024 ACS 5-year.
Across the recorded series it reached a Democratic high of 30.0 points in 1964 and a Republican high of 47.1 points in 1924. Between 2020 and 2024 the district moved 2.8 points toward the Republican candidate; the 2024 margin was 12.6 points.
A population of 64,145, a 80% non-Hispanic-white share, and a median household income of $75,931 describe the district. The district's voting pattern over the last decade is most similar to that of State Senate District 37 and State Senate District 39.
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 →
Iowa 40th State Senate District. Akashic. https://akashic.app/sld-upper/19040/. Accessed May 20, 2026. License: CC BY 4.0.