Fastest Growing Counties in Washington (2025)

County
Rank
Change (2020)
2025 Pop.
2020 Pop.
Wahkiakum County110.59%4,9194,448
Lincoln County29.7%11,98810,928
Pend Oreille County39.67%14,80713,502
Skamania County48.05%13,01012,041
Stevens County57.2%49,94546,591
Douglas County66.78%45,94843,029
Lewis County76.29%87,74882,553
Benton County86.07%219,999207,419
Klickitat County95.9%24,16122,814
Grant County105.46%104,87499,441
Ferry County114.96%7,5557,198
Okanogan County124.93%44,21642,139
Clark County134.88%529,976505,338
Mason County144.23%68,82566,034
Columbia County154%4,1073,949
Pacific County163.89%24,41023,495
Kittitas County173.77%46,28044,599
Garfield County183.53%2,3752,294
Whatcom County193.13%234,561227,449
Cowlitz County203.11%114,464111,014
San Juan County212.96%18,35417,826
Franklin County222.87%99,93897,150
Jefferson County232.85%34,00233,061
Snohomish County242.83%853,379829,933
Grays Harbor County252.55%77,78875,855
Spokane County262.53%554,885541,175
Whitman County272.24%48,87847,807
Skagit County281.31%131,607129,902
Thurston County291.26%299,731295,998
Asotin County301.12%22,57522,324
Pierce County311.03%933,130923,589
Chelan County320.85%79,91579,238
Kitsap County330.55%277,348275,823
King County340.41%2,283,5182,274,282
Adams County350.28%20,66420,607
Clallam County360.15%77,48077,367
Yakima County37-0.33%255,891256,733
Island County38-1.79%85,43786,998
Walla Walla County39-2.59%60,99862,623

Washington County Growth Overview

Washington's counties show varied growth patterns from 2020 to 2025. Wahkiakum County leads with 10.59% annualized growth, followed by Lincoln County (9.7%) and Pend Oreille County (9.67%). The largest counties are King County (2,283,518), Pierce County (933,130), and Snohomish County (853,379). Of the 39 counties in Washington, 36 are growing while just 3 have experienced population decline. Overall, counties averaged 3.52% annualized growth, with total population growing by 1.88% annually.