Somerville leans slightly Democratic by roughly 12 points: about 56% of voters vote Democratic and 44% Republican.
About 72% of adults in Somerville typically vote, above the U.S. average of about 62%. Among adults in Somerville, ~40% vote Democratic, ~32% Republican, and ~28% don't vote. The map below shows estimated turnout by block group.
How Somerville compares
Among cities within 25 miles, Somerville leans more Democratic than 139 of 211 neighbors.
Somerville runs about 7 points more Democratic than New Jersey as a whole.
Politics vary noticeably by neighborhood within Somerville. The south side runs the most Democratic (D+36) and the west side runs the most Republican (R+7), a spread of about 43 points.
Why Somerville 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 Somerville, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 58% of adults in Somerville hold a bachelor's degree, about 30 points above the U.S. average of 28%. Dense areas vote Democratic, and Somerville sits in the top fifth on density (about 81%, above 94% of cities). A high never-married share predicts Democratic voting, and about 36% of adults in Somerville have never been married, above 89% of cities.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; Somerville, NJ 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 Somerville looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Somerville 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%. High high-school completion lines up with higher turnout, and about 96% of adults in Somerville have completed high school, above 82% of cities. Learn more about the findings and methodology on the political spectrum map.
Nearby Cities
- Bradley Gardens, NJ D+9
- Raritan, NJ D+3
- Green Knoll, NJ D+6
- Bridgewater, NJ Even
- North Branch Depot, NJ R+5
- Finderne, NJ D+9
- Manville, NJ R+10
- Flagtown, NJ R+4
- Hillsborough, NJ D+8
Cities with Similar Populations
- Tukwila, WA D+38
- Willow Spring, NC R+24
- White Oak, MD D+63
- Troy, MO R+45
- Scarborough, ME D+21
- Mountain Home, ID R+44
- Westlake Village, CA D+12
- Springtown, TX R+69
- Henderson, TX R+43
- Pleasant Prairie, WI R+7
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Sources and methodology
Precinct-level voting records used to fit the model come from New Jersey Division 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.