South River, NJ Political Map | Democrat & Republican Areas in South River

By the BestNeighborhood data science team. Last updated May 2026.

South River leans slightly Republican by roughly 14 points: about 43% of voters vote Democratic and 57% Republican.

 

About 61% of adults in South River typically vote, near the U.S. average of about 62%. Among adults in South River, ~26% vote Democratic, ~35% Republican, and ~39% don't vote. The map below shows estimated turnout by block group.

How South River compares

Among cities within 25 miles, South River leans more Republican than 162 of 211 neighbors.

South River runs about 19 points more Republican than New Jersey as a whole. New Jersey leans Democratic overall, while South River is one of the few Republican-leaning pockets.

Politics vary noticeably by neighborhood within South River. The south side is the most Republican-leaning (R+22) and the northeast side is the least Republican-leaning (R+3), a spread of about 19 points.

Why South River 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 South River, not a ranked or complete list of what matters most.

South River votes Republican even though it is densely developed (about 93%, far above the New Jersey average of 61%). State and regional patterns outweigh the Democratic lean that density usually predicts here. A high family-household share predicts Republican voting, and about 76% of households in South River are family households, above 78% of cities. South River runs against the grain of New Jersey, a Republican-leaning pocket in a Democratic-leaning state.

High-school completion, developed land, and voter turnout

Places that combine low high-school-completion share and a heavily developed built environment tend to turn out at a lower rate, as South River, NJ does.

Why turnout in South River looks the way it does

Areas with limited routine healthcare access turn out at lower rates. South River 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 34% of households in South River rent, above 90% of cities. Crowded housing lines up with lower turnout, and about 6% of homes in South River have more than one occupant per room, above 91% of cities. Learn more about the findings and methodology on the political spectrum map.

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.