51503 leans slightly Republican by roughly 14 points: about 43% of voters vote Democratic and 57% Republican.
About 82% of adults in 51503 typically vote, above the U.S. average of about 62%. Among adults in 51503, ~35% vote Democratic, ~47% Republican, and ~18% don't vote. The map below shows estimated turnout by block group.
How 51503 compares
Among zip codes within 15 miles, 51503 leans more Republican than 28 of 39 neighbors.
Politically, 51503 sits close to the rest of Iowa.
Politics vary noticeably by block within 51503. The west side runs the most Democratic (D+3) and the southeast side runs the most Republican (R+31), a spread of about 34 points.
Why 51503 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 51503, not a ranked or complete list of what matters most.
51503 votes Republican even though it is densely developed (about 62%, far above the Iowa average of 16%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Cancer-screening access and voter turnout
Places with high colon-cancer-screening access tend to turn out at a higher rate; 51503, IA sits above the national average on this measure. Cancer screening does not drive turnout; it reflects income, insurance, and healthcare access.
Why turnout in 51503 looks the way it does
Turnout in 51503 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.