21640 leans heavily Republican by roughly 48 points: about 26% of voters vote Democratic and 74% Republican.
About 65% of adults in 21640 typically vote, near the U.S. average of about 62%. Among adults in 21640, ~17% vote Democratic, ~48% Republican, and ~35% don't vote. The map below shows estimated turnout by block group.
How 21640 compares
Among zip codes within 15 miles, 21640 leans more Republican than 17 of 22 neighbors.
21640 runs about 78 points more Republican than Maryland as a whole. Maryland leans Democratic overall, while 21640 is one of the few Republican-leaning pockets.
Why 21640 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 21640, not a ranked or complete list of what matters most.
Car-dependent areas vote Republican. About 91% of residents in 21640 drive to work alone, about 17 points above the U.S. average of 74%. Low college attainment predicts Republican voting, and 21640 sits in the bottom quarter (about 11%, below 92% of zip codes). 21640 runs against the grain of Maryland, a Republican-leaning pocket in a Democratic-leaning state.
Preventive-care access and voter turnout
Places with limited routine preventive-care access tend to turn out at a lower rate; 21640, MD sits in the bottom 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 21640 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 21640 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. The dental-visit rate here is about 49%, about 15 points below the Maryland average of 64%. 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.