Sudbury leans heavily Democratic by roughly 32 points: about 66% of voters vote Democratic and 34% Republican.
About 95% of adults in Sudbury typically vote, above the U.S. average of about 62%. Among adults in Sudbury, ~63% vote Democratic, ~32% Republican, and ~5% don't vote. The map below shows estimated turnout by block group.
How Sudbury compares
Among cities within 25 miles, Sudbury leans more Democratic than 111 of 163 neighbors.
Sudbury runs about 8 points more Democratic than Massachusetts as a whole.
Politics vary noticeably by neighborhood within Sudbury. The northeast side is the most Democratic-leaning (D+40) and the southeast side is the least Democratic-leaning (D+28), a spread of about 13 points.
Why Sudbury 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 Sudbury, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 84% of adults in Sudbury hold a bachelor's degree, about 55 points above the U.S. average of 28%. Dense areas vote Democratic, and Sudbury sits in the top fifth on density (about 47%, above 86% of cities).
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Sudbury, MA sits in the top quarter nationally on this measure. A walkable street grid does not change how people vote; it mostly reflects how urban a place is.
Why turnout in Sudbury looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Sudbury 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 81%, about 21 points above the U.S. average of 60%. Homeowners vote more often than renters, and about 91% of households in Sudbury own their home, about 16 points above the U.S. average of 75%. High high-school completion lines up with higher turnout, and about 99% of adults in Sudbury have completed high school, above 98% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Pine Lake, MA D+32
- Maynard, MA D+38
- Wayland, MA D+36
- West Concord, MA D+53
- Cochituate, MA D+43
- Stow, MA D+34
- Framingham, MA D+32
- Concord, MA D+43
- Marlborough, MA D+21
- Lincoln, MA D+43
Cities with Similar Populations
- Brewster, NY R+9
- Colonia, NJ R+9
- Selah, WA R+36
- North Wilkesboro, NC R+49
- Newberry, SC Even
- Eastchester, NY D+9
- Franklin Park, IL D+6
- Ashland, VA R+5
- Chickasha, OK R+41
- Justin, TX R+40
All Local Stats
Home Services
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.