Population of Counties in Washington (2020)

As of 2019, Washington's most populous county is King County, home to Seattle, with a population of 2,188,649. This represents a population growth of 12.97% since the 2010 census. King County is followed by Piece County (876,764), Snohomish County (801,633), and Spokane County (506,152) in terms of population. These are the only counties with a population of more than 500,000. All four counties have posted significant growth since the census ranging from 7% to almost 13%.

Washington Counties with Fewest Residents

The least populous Washington county is Garfield County with a population of 2,210. This represents a population decline of 2.26% since the last census. Other sparsely populated counties in Washington include Columbia County (4,047), Wahkiakum County (4,264), and Ferry County (7,594). These are the only counties in Washington with a population under 10,000. Three of these counties reported a population decline since 2010. Wahkiakum County had population growth of 7.05% since the last census.

Washington Counties with Rapid Growth

Franklin County has boasted the highest population growth rate in Washington since the last census, growing 16.48% to 92,125. Four other cities have experienced population growth above 12%: King County (12.97%), Kittitas County (12.74%), Benton County (12.30%), and Snohomish County (12.05%). The county with the largest negative growth is Garfield County at -2.26%.

Name 2020 Population Growth Since 2010
King County2,291,03018.19%
Pierce County919,49515.60%
Snohomish County838,62517.21%
Spokane County532,03712.70%
Clark County496,58716.38%
Thurston County298,67918.06%
Kitsap County276,3159.79%
Yakima County253,5843.81%
Whatcom County233,75515.98%
Benton County208,72518.28%
Skagit County132,56613.35%
Cowlitz County113,16110.56%
Grant County100,35112.04%
Franklin County98,80724.94%
Island County86,81010.32%
Lewis County82,3529.07%
Clallam County78,78710.18%
Chelan County78,1507.41%
Grays Harbor County76,5975.15%
Mason County68,91913.47%
Walla Walla County61,4624.31%
Whitman County50,68513.15%
Kittitas County49,77821.44%
Stevens County46,4466.86%
Douglas County44,38715.25%
Okanogan County42,6003.33%
Jefferson County32,8059.75%
Klickitat County22,82112.00%
Asotin County22,8165.02%
Pacific County22,7408.92%
Adams County19,9155.99%
San Juan County17,93413.62%
Pend Oreille County14,0808.73%
Skamania County12,0988.84%
Lincoln County11,0624.61%
Ferry County7,7672.96%
Wahkiakum County4,71818.45%
Columbia County4,1310.90%
Garfield County2,3313.10%