51631 is a Republican stronghold. About 21% of voters here vote Democratic and 79% Republican.
About 74% of adults in 51631 typically vote, above the U.S. average of about 62%. Among adults in 51631, ~16% vote Democratic, ~58% Republican, and ~26% don't vote. The map below shows estimated turnout by block group.
How 51631 compares
Among zip codes within 15 miles, 51631 leans more Republican than 6 of 13 neighbors.
51631 runs about 45 points more Republican than Iowa as a whole.
Why 51631 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 51631, not a ranked or complete list of what matters most.
Areas with a high white share and below-average college attainment vote Republican. In 51631, about 94% of residents are non-Hispanic white, about 22 points above the U.S. average of 72%; about 18% of adults hold a bachelor's degree, about 6 points below the Iowa average of 24%. Rural areas vote Republican, and 51631 sits in the bottom quarter on density (about 6%, below 76% of zip codes).
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; 51631, IA sits in the top quarter nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in 51631 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 51631 is in the top quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 69%, about 9 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 89% of households in 51631 own their home, above 84% of zip codes. High high-school completion lines up with higher turnout, and about 97% of adults in 51631 have completed high school, above 87% of zip codes. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
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.