Waltham leans heavily Democratic by roughly 44 points: about 72% of voters vote Democratic and 28% Republican.
About 65% of adults in Waltham typically vote, near the U.S. average of about 62%. Among adults in Waltham, ~47% vote Democratic, ~18% Republican, and ~35% don't vote. The map below shows estimated turnout by block group.
How Waltham compares
Among cities within 25 miles, Waltham leans more Democratic than 132 of 163 neighbors.
Waltham runs about 18 points more Democratic than Massachusetts as a whole.
Politics vary noticeably by neighborhood within Waltham. The south side is the most Democratic-leaning (D+60) and the northwest side is the least Democratic-leaning (D+28), a spread of about 33 points.
Why Waltham 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 Waltham, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 89% of residents in Waltham live in densely developed areas, about 53 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Waltham sits in the top quarter (about 57%, above 96% of cities). A high never-married share predicts Democratic voting, and about 47% of adults in Waltham have never been married, above 97% of cities.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Waltham, MA 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 Waltham looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Waltham 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%. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Newtonville, MA D+63
- Newton, MA D+58
- Auburndale, MA D+59
- Watertown Town, MA D+57
- Belmont, MA D+63
- Weston, MA D+33
- Newton Lower Falls, MA D+54
- Waban, MA D+57
- Watertown, MA D+77
- Lexington, MA D+54
Cities with Similar Populations
- Castro Valley, CA D+33
- San Luis Obispo, CA D+39
- Lorain, OH D+14
- Hanford, CA R+15
- Casa Grande, AZ R+14
- Arcadia, CA D+14
- Joplin, MO R+33
- Northglenn, CO D+12
- Lake Forest, CA D+2
- Casper, WY R+37
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Sources and methodology
Precinct-level voting records used to fit the model come from Massachusetts Secretary of the Commonwealth, 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.