RANKING · 2025 ESTIMATES · 39 SHOWN OF 39

Most densely populated, Washington counties

Washington counties ranked by residents per square mile (2025). This list covers the 39 counties in Washington that qualify, ranked against each other statewide. The median across all 39 is 39.

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SAME RANKING BYCities States Metros

YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01King County, WAWA2,344,9391,108+35%

02Clark County, WAWA532,119847+54%

03Kitsap County, WAWA283,374717+22%

04Pierce County, WAWA946,288567+35%

05▲1Thurston County, WAWA304,261421+47%

06▲1Snohomish County, WAWA870,656417+44%

07▼2Island County, WAWA85,657411+20%

08Spokane County, WAWA558,344316+34%

09Benton County, WAWA221,722130+56%

10Whatcom County, WAWA236,392112+42%

11San Juan County, WAWA18,577107+32%

12Cowlitz County, WAWA114,885101+24%

13Franklin County, WAWA102,61283+108%

14Skagit County, WAWA132,97577+29%

15Mason County, WAWA71,16574+44%

16Yakima County, WAWA259,18560+16%

17Walla Walla County, WAWA62,36149+13%

18Clallam County, WAWA78,20245+21%

19Grays Harbor County, WAWA78,14441+16%

20Grant County, WAWA105,72739+42%

21▲1Lewis County, WAWA88,06237+28%

22▼1Asotin County, WAWA22,54535+10%

23Chelan County, WAWA81,94128+23%

24Pacific County, WAWA24,35726+16%

25Douglas County, WAWA46,47326+43%

26Whitman County, WAWA48,51222+19%

27Kittitas County, WAWA48,80321+46%

28Stevens County, WAWA49,66820+24%

29Jefferson County, WAWA33,97019+31%

30Wahkiakum County, WAWA4,87319+27%

31Klickitat County, WAWA24,33113+27%

32Adams County, WAWA21,48811+31%

33Pend Oreille County, WAWA14,45710+23%

34Okanogan County, WAWA45,2309+14%

35Skamania County, WAWA12,6698+28%

36Lincoln County, WAWA11,9825+18%

37Columbia County, WAWA4,1415+2%

38Ferry County, WAWA7,5173+4%

39Garfield County, WAWA2,4163+1%

SHOWING 1–39 OF 39

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU POPULATION ESTIMATES