Grantham leans Democratic by roughly 22 points: about 61% of voters vote Democratic and 39% Republican.
About 64% of adults in Grantham typically vote, near the U.S. average of about 62%. Among adults in Grantham, ~39% vote Democratic, ~25% Republican, and ~36% don't vote. The map below shows estimated turnout by block group.
How Grantham compares
Among cities within 25 miles, Grantham leans more Democratic than 134 of 138 neighbors.
Grantham runs about 24 points more Democratic than Pennsylvania as a whole. Pennsylvania is roughly evenly split, and Grantham sits clearly on the Democratic side.
Politics vary noticeably by neighborhood within Grantham. The northeast side runs the most Democratic (D+29) and the south side runs the most Republican (R+29), a spread of about 57 points.
Why Grantham 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 Grantham, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 64% of adults in Grantham hold a bachelor's degree, about 36 points above the U.S. average of 28%. Dense areas vote Democratic, and Grantham sits in the top fifth on density (about 44%, above 85% of cities). A high never-married share predicts Democratic voting, and about 84% of adults in Grantham have never been married, in the top fraction of cities.
Population density and Democratic lean
Places with high population density tend to lean Democratic; Grantham, PA sits in the top tenth nationally on this measure.
Why turnout in Grantham looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Grantham 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 74%, about 14 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Dillsburg, PA R+35
- Mechanicsburg, PA R+3
- Shiremanstown, PA Even
- Franklintown, PA R+45
- Lewisberry, PA R+38
- Camp Hill, PA D+10
- Lower Allen, PA Even
- Boiling Springs, PA R+24
Cities with Similar Populations
- Green Park, MO D+5
- Nixon, TX R+34
- Blackville, SC D+28
- Waldoboro, ME R+19
- Jamesville, NC R+31
- Lakeview, MI R+42
- Sumas, WA R+38
- Sandstone, MN R+31
- Suttons Bay, MI D+9
- Fairfield, PA R+48
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Sources and methodology
Precinct-level voting records used to fit the model come from Pennsylvania Department of State, Bureau of 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.