21403 leans heavily Democratic by roughly 34 points: about 67% of voters vote Democratic and 33% Republican.
About 73% of adults in 21403 typically vote, above the U.S. average of about 62%. Among adults in 21403, ~49% vote Democratic, ~24% Republican, and ~27% don't vote. The map below shows estimated turnout by block group.
How 21403 compares
Among zip codes within 15 miles, 21403 leans more Democratic than 26 of 30 neighbors.
21403 runs about 6 points more Democratic than Maryland as a whole.
Politics vary noticeably by block within 21403. The northwest side is the most Democratic-leaning (D+43) and the southwest side is the least Democratic-leaning (D+16), a spread of about 27 points.
Why 21403 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 21403, not a ranked or complete list of what matters most.
Areas with high college attainment vote Democratic. About 55% of adults in 21403 hold a bachelor's degree, about 26 points above the U.S. average of 28%. Density combined with diversity predicts Democratic voting, and non-Hispanic white share in 21403 is about 65%, below 72% of zip codes.
Preventive-care access and voter turnout
Places with strong routine preventive-care access tend to turn out at a higher rate; 21403, MD sits in the top quarter 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 21403 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 21403 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 69%, about 9 points above the U.S. average of 60%. 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 Maryland State Board 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.