20603 is a Democratic stronghold. About 81% of voters here vote Democratic and 19% Republican.
About 82% of adults in 20603 typically vote, above the U.S. average of about 62%. Among adults in 20603, ~66% vote Democratic, ~16% Republican, and ~18% don't vote. The map below shows estimated turnout by block group.
How 20603 compares
Among zip codes within 15 miles, 20603 leans more Democratic than 27 of 38 neighbors.
20603 runs about 34 points more Democratic than Maryland as a whole.
Politics vary noticeably by block within 20603. The southeast side is the most Democratic-leaning (D+71) and the west side is the least Democratic-leaning (D+47), a spread of about 24 points.
Why 20603 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 20603, not a ranked or complete list of what matters most.
Density combined with diversity predicts Democratic voting. Non-Hispanic white share in 20603 is about 17%, about 55 points below the U.S. average of 72%. High college attainment predicts Democratic voting, and 20603 sits in the top quarter (about 40%, above 81% of zip codes). A high never-married share predicts Democratic voting, and about 33% of adults in 20603 have never been married, above 75% of zip codes.
Paved land cover and Democratic lean
Places with extensive paved surfaces tend to lean Democratic; 20603, MD sits in the top quarter 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 20603 looks the way it does
Areas with high high-school completion turn out at higher rates. About 96% of adults in 20603 have completed high school, about 7 points above the U.S. average of 90%. 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.