Onslow leans heavily Republican by roughly 40 points: about 30% of voters vote Democratic and 70% Republican.
About 79% of adults in Onslow typically vote, above the U.S. average of about 62%. Among adults in Onslow, ~24% vote Democratic, ~55% Republican, and ~21% don't vote. The map below shows estimated turnout by block group.
How Onslow compares
Among cities within 25 miles, Onslow leans more Republican than 28 of 52 neighbors.
Onslow runs about 27 points more Republican than Iowa as a whole.
Why Onslow leans the way it does
This analysis examined 14,881 data points per city to find what predicts political lean and turnout. The items below are a few correlations that stood out for Onslow, not a ranked or complete list of what matters most.
Areas with many family households vote Republican. About 77% of households in Onslow are family households, about 11 points above the U.S. average of 67%.
Population density and Republican lean
Places with low population density tend to lean Republican; Onslow, IA sits in the bottom quarter nationally on this measure.
Why turnout in Onslow looks the way it does
Areas with high high-school completion turn out at higher rates. About 96% of adults in Onslow have completed high school, about 6 points above the U.S. average of 90%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Wyoming, IA R+41
- Center Junction, IA R+39
- Monmouth, IA R+43
- Scotch Grove, IA R+37
- Hale, IA R+41
- Baldwin, IA R+45
- Oxford Junction, IA R+42
- Olin, IA R+40
- Nashville, IA R+44
Cities with Similar Populations
- Deschutes Junction, OR R+17
- Alba, PA R+56
- Jay City, IN R+74
- Cornersville, MS R+74
- Potts Grove, PA R+54
- Morrison, WI R+48
- Eddyville, IL R+59
- Golf, IL D+33
- Oil City, KY R+54
- Kellnersville, WI R+47
All Local Stats
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Sources and methodology
Precinct-level voting records used to fit the model come from Iowa Secretary of State, Elections, distributed by the Voting and Election Science Team. Demographic inputs come from the U.S. Census Bureau (ACS 5-year estimates and the 2020 Decennial Census). Health and environmental inputs come from the CDC (PLACES and the Environmental Justice Index). Land cover comes from the USGS and EPA. Election-day and lead-up weather come from PRISM 4km daily grids and the NOAA Global Historical Climatology Network. Mail-voting and election-administration patterns come from the MIT Election Lab's Survey of the Performance of American Elections. Block-group crime detail comes from CrimeGrade. Internet data and modeling support provided by ISPreports.org.
Modeling and analysis by the BestNeighborhood data science team. Full methodology and findings: political spectrum map.
Methodology reviewed by the BestNeighborhood data team. Last updated May 2026.