Marion County leans heavily Republican by roughly 34 points: about 33% of voters vote Democratic and 67% Republican.
About 92% of adults in Marion County typically vote, above the U.S. average of about 62%. Among adults in Marion County, ~30% vote Democratic, ~62% Republican, and ~8% don't vote. The map below shows estimated turnout by block group.
How Marion County compares
Among counties within 50 miles, Marion County leans more Republican than 7 of 15 neighbors.
Marion County runs about 21 points more Republican than Iowa as a whole.
Politics vary noticeably by city within Marion County. The southeast side is the most Republican-leaning (R+51) and the northeast side is the least Republican-leaning (R+23), a spread of about 27 points.
Why Marion County leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Marion County. The lean here lands roughly where demographic data alone would predict.
High-school completion, uninsured rate, and voter turnout
Places that combine high-school-completion-heavy adults and a low uninsured rate tend to turn out at a higher rate, as Marion County, IA does.
Why turnout in Marion County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Marion County 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 71%, about 11 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 95% of adults in Marion County have completed high school, above 90% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Mahaska County, IA R+38
- Jasper County, IA R+28
- Monroe County, IA R+43
- Lucas County, IA R+44
- Warren County, IA R+24
- Poweshiek County, IA R+19
- Polk County, IA D+12
- Wapello County, IA R+26
- Appanoose County, IA R+43
- Clarke County, IA R+41
Counties with Similar Populations
- Accomack County, VA R+16
- Daviess County, IN R+59
- Petersburg City, VA D+71
- Lincoln County, OK R+64
- Lumpkin County, GA R+46
- Caroline County, MD R+34
- Morton County, ND R+49
- Lee County, IA R+27
- Bureau County, IL R+27
- Botetourt County, VA R+45
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.