Middlesex County leans heavily Democratic by roughly 36 points: about 68% of voters vote Democratic and 32% Republican.
About 72% of adults in Middlesex County typically vote, above the U.S. average of about 62%. Among adults in Middlesex County, ~49% vote Democratic, ~23% Republican, and ~28% don't vote. The map below shows estimated turnout by block group.
How Middlesex County compares
Among counties within 50 miles, Middlesex County leans more Democratic than 8 of 9 neighbors.
Middlesex County runs about 12 points more Democratic than Massachusetts as a whole.
Politics vary noticeably by city within Middlesex County. The southeast side is the most Democratic-leaning (D+72) and the north side is the least Democratic-leaning (D+15), a spread of about 57 points.
Why Middlesex 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 Middlesex County, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 60% of adults in Middlesex County hold a bachelor's degree, about 31 points above the U.S. average of 28%. Dense areas vote Democratic, and Middlesex County sits in the top fifth on density (about 81%, above 95% of counties). A high never-married share predicts Democratic voting, and about 36% of adults in Middlesex County have never been married, above 87% of counties.
Walkability and Democratic lean
Places with a highly walkable street grid tend to lean Democratic; Middlesex County, MA sits in the top tenth 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 Middlesex County looks the way it does
Areas with strong routine healthcare access turn out at higher rates. Middlesex County 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 73%, about 13 points above the U.S. average of 60%. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Suffolk County, MA D+53
- Norfolk County, MA D+30
- Essex County, MA D+18
- Worcester County, MA D+12
- Hillsborough County, NH D+11
- Rockingham County, NH D+6
- Plymouth County, MA D+11
- Providence County, RI D+20
- Bristol County, MA Even
- Bristol County, RI D+17
Counties with Similar Populations
- Philadelphia County, PA D+56
- Sacramento County, CA D+20
- Alameda County, CA D+49
- New York County, NY D+62
- Palm Beach County, FL D+5
- Bronx County, NY D+43
- Wayne County, MI D+33
- Hillsborough County, FL Even
- Suffolk County, NY R+8
- Orange County, FL D+14
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.