16121 leans heavily Democratic by roughly 50 points: about 75% of voters vote Democratic and 25% Republican.
About 66% of adults in 16121 typically vote, near the U.S. average of about 62%. Among adults in 16121, ~50% vote Democratic, ~16% Republican, and ~34% don't vote. The map below shows estimated turnout by block group.
How 16121 compares
Among zip codes within 15 miles, 16121 leans more Democratic than 38 of 43 neighbors.
16121 runs about 52 points more Democratic than Pennsylvania as a whole. Pennsylvania is roughly evenly split, and 16121 sits clearly on the Democratic side.
Politics vary noticeably by block within 16121. The southwest side is the most Democratic-leaning (D+65) and the southeast side is the least Democratic-leaning (D+32), a spread of about 33 points.
Why 16121 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 16121, not a ranked or complete list of what matters most.
Dense areas vote Democratic. About 97% of residents in 16121 live in densely developed areas, about 60 points above the U.S. average of 36%. A high never-married share predicts Democratic voting, and about 37% of adults in 16121 have never been married, above 83% of zip codes. 16121 runs against the grain of Pennsylvania, a Democratic-leaning outlier in a roughly evenly split state.
Population density and Democratic lean
Places with high population density tend to lean Democratic; 16121, PA sits in the top quarter nationally on this measure.
Why turnout in 16121 looks the way it does
Limited routine healthcare access lines up with lower turnout, and 16121 sits in the bottom quarter on routine-care measures. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
Sources and methodology
Precinct-level voting records used to fit the model come from Pennsylvania Department of State, Bureau 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.