Union County leans Democratic by roughly 26 points: about 63% of voters vote Democratic and 37% Republican.
About 61% of adults in Union County typically vote, near the U.S. average of about 62%. Among adults in Union County, ~39% vote Democratic, ~23% Republican, and ~38% don't vote. The map below shows estimated turnout by block group.
How Union County compares
Among counties within 50 miles, Union County leans more Democratic than 15 of 22 neighbors.
Union County runs about 20 points more Democratic than New Jersey as a whole.
Politics vary noticeably by city within Union County. The southwest side is the most Democratic-leaning (D+44) and the south side is the least Democratic-leaning (D+15), a spread of about 29 points.
Why Union 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 Union County, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 96% of residents in Union County live in densely developed areas, about 60 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and Union County sits in the top quarter (about 39%, above 90% of counties). A high never-married share predicts Democratic voting, and about 37% of adults in Union County have never been married, above 89% of counties.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; Union County, NJ sits in the top tenth nationally on this measure. Paved ground does not change how people vote; it mostly reflects how urban and built-up a place is.
Why turnout in Union County looks the way it does
Areas with limited routine healthcare access turn out at lower rates. Union County is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. Renters vote less often than owners, and about 42% of households in Union County rent, about 17 points above the U.S. average of 25%. Crowded housing lines up with lower turnout, and about 6% of homes in Union County have more than one occupant per room, above 95% of counties. Learn more about the findings and methodology on the political spectrum map.
Nearby Counties
- Essex County, NJ D+48
- Richmond County, NY R+21
- Middlesex County, NJ D+11
- Hudson County, NJ D+27
- Somerset County, NJ D+15
- Morris County, NJ Even
- Kings County, NY D+34
- New York County, NY D+62
- Passaic County, NJ D+4
- Bergen County, NJ D+5
Counties with Similar Populations
- Delaware County, PA D+27
- Bristol County, MA Even
- New Castle County, DE D+33
- Jefferson County, CO D+18
- Douglas County, NE D+17
- Baltimore City, MD D+72
- Anne Arundel County, MD D+17
- Pasco County, FL R+24
- Dane County, WI D+48
- Volusia County, FL R+17
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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.