Herndon leans heavily Republican by roughly 42 points: about 29% of voters vote Democratic and 71% Republican.
About 77% of adults in Herndon typically vote, above the U.S. average of about 62%. Among adults in Herndon, ~22% vote Democratic, ~55% Republican, and ~23% don't vote. The map below shows estimated turnout by block group.
How Herndon compares
Among cities within 25 miles, Herndon leans more Republican than 22 of 41 neighbors.
Herndon runs about 29 points more Republican than Iowa as a whole.
Why Herndon leans the way it does
Density, race composition, education, and family structure all sit close to their national averages in Herndon. 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; Herndon, IA sits in the top quarter 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 Herndon looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Herndon 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 69%, about 9 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Jamaica, IA R+42
- Bagley, IA R+44
- Yale, IA R+42
- Dawson, IA R+39
- Rippey, IA R+50
- Jefferson, IA R+28
- Bayard, IA R+49
- Cooper, IA R+42
- Panora, IA R+37
- Grand Junction, IA R+52
Cities with Similar Populations
- Olema, CA D+43
- Meadow Creek, WV R+57
- Upperville, NY R+49
- Upton, IN R+53
- Orient, SD R+66
- Briggsville, AR R+71
- La Joya, NM R+18
- Cornhouse, AL R+56
- Dexter, IL R+66
- Frisco, IL R+68
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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.