51639 leans heavily Republican by roughly 48 points: about 26% of voters vote Democratic and 74% Republican.
About 80% of adults in 51639 typically vote, above the U.S. average of about 62%. Among adults in 51639, ~21% vote Democratic, ~59% Republican, and ~20% don't vote. The map below shows estimated turnout by block group.
How 51639 compares
Among zip codes within 15 miles, 51639 leans more Republican than 5 of 9 neighbors.
51639 runs about 36 points more Republican than Iowa as a whole.
Why 51639 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 51639, not a ranked or complete list of what matters most.
Areas with a high white share and below-average college attainment vote Republican. In 51639, 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 7 points below the Iowa average of 24%. Rural areas vote Republican, and 51639 sits in the bottom quarter on density (about 5%, below 81% of zip codes).
Never-married share, developed land, and voter turnout
Places that combine a low never-married share and a rural land-use pattern tend to turn out at a higher rate, as 51639, IA does.
Why turnout in 51639 looks the way it does
Turnout in 51639 sits close to the national pattern. Routine healthcare access, homeownership, education, and food security all land near their national averages here. 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.