Madison County leans heavily Republican by roughly 42 points: about 29% of voters vote Democratic and 71% Republican.
About 90% of adults in Madison County typically vote, above the U.S. average of about 62%. Among adults in Madison County, ~26% vote Democratic, ~64% Republican, and ~10% don't vote. The map below shows estimated turnout by block group.
How Madison County compares
Among counties within 50 miles, Madison County leans more Republican than 6 of 13 neighbors.
Madison County runs about 28 points more Republican than Iowa as a whole.
Why Madison County leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Madison County. The lean here lands roughly where demographic data alone would predict.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Madison County, IA sits in the top tenth nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in Madison County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Madison 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%. Homeowners vote more often than renters, and about 81% of households in Madison County own their home, above 85% of counties. High high-school completion lines up with higher turnout, and about 97% of adults in Madison County have completed high school, above 98% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Dallas County, IA R+7
- Warren County, IA R+24
- Clarke County, IA R+41
- Adair County, IA R+46
- Polk County, IA D+12
- Union County, IA R+33
- Guthrie County, IA R+41
- Lucas County, IA R+44
- Ringgold County, IA R+50
- Adams County, IA R+46
Counties with Similar Populations
- Idaho County, ID R+64
- La Paz County, AZ R+28
- Lee County, SC D+20
- Richland County, ND R+38
- Phillips County, AR D+20
- Burnett County, WI R+32
- Crawford County, IA R+37
- Madison County, AR R+61
- Socorro County, NM Even
- Lafayette County, WI R+31
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.