Washington voted Democratic for president by 18.2 points in 2024, down a single point from 19.2 in 2020 — one of the smallest changes in the country in a cycle that moved most states toward Donald Trump. The state has backed the Democratic nominee in every election since 1988; the last Republican to carry it was Ronald Reagan in 1984. But the 18-point statewide figure hides a deep split, and the line that draws it is geographic: the Cascade Mountains, which separate the rain-fed Puget Sound metropolis on the west from the dry interior on the east. The two sides vote as if they were different states.
West of the range, five counties around Puget Sound cast 58.9 percent of the statewide vote. King County, which holds Seattle, is the engine: it voted Democratic by 51.3 points in 2024, the state’s widest margin, and its 580,413-vote cushion is four-fifths of Washington’s 714,926-vote statewide margin. Pierce County around Tacoma went Democratic by 10.7, Snohomish by 18.8, Thurston around Olympia by 20.3, and Whatcom — home to Western Washington University in Bellingham — by 24.7. The Seattle area is the demographic core: Asian residents are 9.7 percent of the state, the Chinese and Asian Indian populations each above two percent, tracking the technology economy that has reshaped the region.
East of the Cascades the pattern reverses. The Columbia Basin and the wheat country run heavily Republican: Lincoln County voted Republican by 50.3 points, the state’s widest margin, and Garfield County by 47.6; Benton County in the Tri-Cities by 21.7 and Yakima by 14.3. The exception is Spokane, the largest eastern city, which held Republican by just 4.9 points — closer than 8.3 in 2016 — the eastern swing ground in a region otherwise lopsided. Underneath sits an affluent, secular profile: seventh of the fifty states in median household income at $98,141, eleventh in bachelor’s degrees, and thirteenth in the share claiming no religion, at 58.8 percent.