- Lead
- 3,105
- Total
- 25,232
- vs nation
- D+13.8
Iowa 31st State Senate District
President margin by year
Place winner margin
President results by year
Modeled candidate-vote estimate on current district boundaries
- Lead
- 6,163
- Total
- 28,284
- vs nation
- D+17.3
- Lead
- 5,711
- Total
- 27,935
- vs nation
- D+18.4
- Lead
- 9,870
- Total
- 29,561
- vs nation
- D+29.5
- Lead
- 10,179
- Total
- 28,639
- vs nation
- D+28.3
- Lead
- 7,122
- Total
- 27,740
- vs nation
- D+28.1
- Lead
- 6,077
- Total
- 24,036
- vs nation
- D+24.8
- Lead
- 7,344
- Total
- 23,268
- vs nation
- D+23.0
Key facts
- 2024 presidential margin
- D+12.3MIT Election Lab
- Population
- 64,3062024 5-year
- Population density
- 1,200 / sq mi2024 5-year · TIGER/Line
- Land area
- 53.6 sq miTIGER/Line
- Median household income
- $56,6622024 5-year
- White (non-Hispanic)
- 65.0%2024 5-year
- Black
- 18.3%2024 5-year
- Hispanic / Latino
- 7.3%2024 5-year
- Peak Democratic margin
- D+35.5 in 2008MIT Election Lab
- Peak Republican margin
- R+48.3 in 1920MIT Election Lab
- Most similar
- State Senate District 39, IA · twin score 91.5
presidential history
Party record book
Iowa 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
Lyndon B. Johnson1964
67.3%
14,977 votes · D+34.7 · modeled estimate
Runner-up · Barack Obama, 2008 · 67.0%
Republican
Warren G. Harding1920
71.5%
6,223 votes · R+48.3 · modeled estimate
Runner-up · Herbert Hoover, 1928 · 63.1%
Most votes
Largest number of votes cast for the party’s presidential nominee here.
Democratic
Barack Obama2012
19,495votes
65.9% of the vote · D+33.4 · modeled estimate
Runner-up · Barack Obama, 2008 · 19,194 votes
Republican
Ronald Reagan1984
11,769votes
43.0% of the vote · D+13.2 · modeled estimate
Runner-up · Gerald Ford, 1976 · 11,310 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
+34.9pts D vs U.S.
Place D+27.2 · U.S. R+7.7 · modeled estimate
Runner-up · Walter Mondale, 1984 · +31.4 pts
Republican
Warren G. Harding1920
+22.1pts R vs U.S.
Place R+48.3 · U.S. R+26.2 · modeled estimate
Runner-up · Calvin Coolidge, 1924 · +19.3 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 |
|---|---|---|---|---|
| 2020 | D | 55.1%17,695 | 44.9%14,394 | 32,089 |
| 2018 | D | 57.3%14,558 | 42.7%10,846 | 25,404 |
Iowa Senate District 31 leans heavily Republican in statewide contests, with its largely rural and small-town electorate delivering some of the state's more consistent margins. Demographic shifts here have trended toward consolidating that alignment over the past decade.
Across the recorded series it reached a Democratic high of 35.5 points in 2008 and a Republican high of 48.3 points in 1920. Between 2020 and 2024 the district moved 9.5 points toward the Republican candidate; the 2024 margin was 12.3 points.
A population of 64,306, a 65% non-Hispanic-white share, and a median household income of $56,662 describe the district. The district's voting pattern over the last decade is most similar to that of State Senate District 39 and State Senate District 49.
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 31st State Senate District. Akashic. https://akashic.app/sld-upper/19031/. Accessed May 20, 2026. License: CC BY 4.0.