21904 leans heavily Republican by roughly 46 points: about 27% of voters vote Democratic and 73% Republican.
About 80% of adults in 21904 typically vote, above the U.S. average of about 62%. Among adults in 21904, ~22% vote Democratic, ~58% Republican, and ~20% don't vote. The map below shows estimated turnout by block group.
How 21904 compares
Among zip codes within 15 miles, 21904 leans more Republican than 16 of 24 neighbors.
21904 runs about 74 points more Republican than Maryland as a whole. Maryland leans Democratic overall, while 21904 is one of the few Republican-leaning pockets.
Why 21904 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 21904, not a ranked or complete list of what matters most.
21904 votes against the grain of Maryland. Maryland leans Democratic overall, while 21904 runs about 74 points more Republican. A high family-household share predicts Republican voting, and about 75% of households in 21904 are family households, above 79% of zip codes.
Homeownership and voter turnout
Places with homeowner-heavy households tend to turn out at a higher rate; 21904, MD sits in the top quarter nationally on this measure.
Why turnout in 21904 looks the way it does
Homeowners vote more often than renters. About 90% of households in 21904 own their home, about 13 points above the Maryland average of 77%. 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.