51104 is a true toss-up. About 52% of voters here vote Democratic and 48% Republican.
About 66% of adults in 51104 typically vote, near the U.S. average of about 62%. Among adults in 51104, ~34% vote Democratic, ~32% Republican, and ~34% don't vote. The map below shows estimated turnout by block group.
How 51104 compares
Among zip codes within 15 miles, 51104 leans more Democratic than 17 of 19 neighbors.
51104 runs about 17 points more Democratic than Iowa as a whole. Iowa leans Republican overall, while 51104 is one of the few Democratic-leaning pockets.
Politics vary noticeably by block within 51104. The south side runs the most Democratic (D+22) and the northwest side runs the most Republican (R+11), a spread of about 32 points.
Why 51104 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 51104, not a ranked or complete list of what matters most.
51104 votes against the grain of Iowa. Iowa leans Republican overall, while 51104 runs about 17 points more Democratic.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 51104, IA sits in the top quarter nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in 51104 looks the way it does
Turnout in 51104 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.