Mercer County is a Republican stronghold. About 17% of voters here vote Democratic and 83% Republican.
About 81% of adults in Mercer County typically vote, above the U.S. average of about 62%. Among adults in Mercer County, ~14% vote Democratic, ~67% Republican, and ~19% don't vote. The map below shows estimated turnout by block group.
How Mercer County compares
Among counties within 50 miles, Mercer County leans more Republican than 16 of 17 neighbors.
Mercer County runs about 54 points more Republican than Ohio as a whole.
Politics vary noticeably by city within Mercer County. The southeast side is the most Republican-leaning (R+83) and the east side is the least Republican-leaning (R+52), a spread of about 30 points.
Why Mercer 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 Mercer County, not a ranked or complete list of what matters most.
Car-dependent areas vote Republican. About 87% of residents in Mercer County drive to work alone, about 13 points above the U.S. average of 74%.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Mercer County, OH 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 Mercer County looks the way it does
Areas with high high-school completion turn out at higher rates. About 95% of adults in Mercer County have completed high school, about 5 points above the U.S. average of 90%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Auglaize County, OH R+59
- Jay County, IN R+58
- Adams County, IN R+60
- Van Wert County, OH R+56
- Shelby County, OH R+58
- Darke County, OH R+61
- Allen County, OH R+32
- Randolph County, IN R+55
- Wells County, IN R+56
- Miami County, OH R+42
Counties with Similar Populations
- Erath County, TX R+55
- Vance County, NC D+19
- St. John the Baptist Parish, LA D+27
- Danville City, VA D+32
- Miller County, AR R+26
- Ohio County, WV R+20
- Montrose County, CO R+30
- Union County, PA R+26
- Summit County, UT D+10
- Davie County, NC R+45
Sources and methodology
Precinct-level voting records used to fit the model come from Ohio 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.