Grundy County leans heavily Republican by roughly 42 points: about 29% of voters vote Democratic and 71% Republican.
About 79% of adults in Grundy County typically vote, above the U.S. average of about 62%. Among adults in Grundy County, ~23% vote Democratic, ~56% Republican, and ~21% don't vote. The map below shows estimated turnout by block group.
How Grundy County compares
Among counties within 50 miles, Grundy County leans more Republican than 10 of 12 neighbors.
Grundy County runs about 29 points more Republican than Iowa as a whole.
Politics vary noticeably by city within Grundy County. The north side is the most Republican-leaning (R+54) and the southeast side is the least Republican-leaning (R+36), a spread of about 18 points.
Why Grundy County leans the way it does
This analysis examined 14,881 data points per county to find what predicts political lean and turnout. The items below are a few correlations that stood out for Grundy County, not a ranked or complete list of what matters most.
Rural areas with a high white share vote Republican. Grundy County sits in the bottom quarter on density and about 95% of residents are non-Hispanic white, about 22 points above the U.S. average of 72%.
Paved land cover and Republican lean
Places with little paved surface tend to lean Republican; Grundy County, IA sits in the bottom 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 Grundy County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Grundy 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 72%, about 12 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 85% of households in Grundy County own their home, above 95% of counties. High high-school completion lines up with higher turnout, and about 97% of adults in Grundy County have completed high school, in the top fraction of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Black Hawk County, IA D+3
- Butler County, IA R+43
- Hardin County, IA R+40
- Tama County, IA R+25
- Marshall County, IA R+17
- Bremer County, IA R+25
- Franklin County, IA R+43
- Benton County, IA R+36
- Buchanan County, IA R+36
- Poweshiek County, IA R+19
Counties with Similar Populations
- Appanoose County, IA R+43
- Sumter County, AL D+43
- Stone County, AR R+63
- Menard County, IL R+41
- Morgan County, UT R+63
- Butler County, KY R+67
- Northampton County, VA Even
- Monroe County, WV R+63
- Pamlico County, NC R+37
- Colfax County, NM R+10
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.