99203 leans heavily Democratic by roughly 42 points: about 71% of voters vote Democratic and 29% Republican.
About 90% of adults in 99203 typically vote, above the U.S. average of about 62%. Among adults in 99203, ~64% vote Democratic, ~26% Republican, and ~10% don't vote. The map below shows estimated turnout by block group.
How 99203 compares
Among zip codes within 15 miles, 99203 leans more Democratic than 29 of 31 neighbors.
99203 runs about 24 points more Democratic than Washington as a whole.
Politics vary noticeably by block within 99203. The north side is the most Democratic-leaning (D+53) and the southeast side is the least Democratic-leaning (D+26), a spread of about 27 points.
Why 99203 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 99203, not a ranked or complete list of what matters most.
Dense areas vote Democratic. More than 99% of residents in 99203 live in densely developed areas, about 63 points above the U.S. average of 36%. High college attainment predicts Democratic voting, and 99203 sits in the top quarter (about 61%, above 95% of zip codes).
Population density and Democratic lean
Places with high population density tend to lean Democratic; 99203, WA sits in the top quarter nationally on this measure.
Why turnout in 99203 looks the way it does
Areas with strong routine healthcare access turn out at higher rates. 99203 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 73%, about 13 points above the U.S. average of 60%. High high-school completion lines up with higher turnout, and about 99% of adults in 99203 have completed high school, above 98% of zip codes. 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 Washington Secretary of State, 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.