Herculaneum leans heavily Republican by roughly 36 points: about 32% of voters vote Democratic and 68% Republican.
About 70% of adults in Herculaneum typically vote, above the U.S. average of about 62%. Among adults in Herculaneum, ~22% vote Democratic, ~48% Republican, and ~30% don't vote. The map below shows estimated turnout by block group.
How Herculaneum compares
Among cities within 25 miles, Herculaneum leans more Republican than 36 of 102 neighbors.
Herculaneum runs about 17 points more Republican than Missouri as a whole.
Politics vary noticeably by neighborhood within Herculaneum. The east side is the most Republican-leaning (R+44) and the south side is the least Republican-leaning (R+31), a spread of about 13 points.
Why Herculaneum leans the way it does
This analysis examined 14,881 data points per city to find what predicts political lean and turnout. The items below are a few correlations that stood out for Herculaneum, not a ranked or complete list of what matters most.
Herculaneum votes Republican even though it is densely developed (about 53%, far above the Missouri average of 22%). State and regional patterns outweigh the Democratic lean that density usually predicts here.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Herculaneum, MO 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 Herculaneum looks the way it does
Turnout in Herculaneum sits close to the national pattern. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Crystal City, MO R+38
- Pevely, MO R+43
- Festus, MO R+42
- Barnhart, MO R+42
- Valmeyer, IL R+56
- Hillsboro, MO R+52
- Selma, MO R+50
- Plattin, MO R+57
- Olympian Village, MO R+55
Cities with Similar Populations
- Breese, IL R+53
- Yaphank, NY R+22
- Cochranville, PA R+21
- Avra Valley, AZ R+28
- East Earl, PA R+57
- Goodview, VA R+54
- Rothschild, WI R+6
- Chocowinity, NC R+35
- Freeland, WA D+46
- Momence, IL R+25
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Sources and methodology
Precinct-level voting records used to fit the model come from Missouri 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.