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 County2,233,16315.21%
Pierce County891,29912.06%
Snohomish County814,90113.89%
Spokane County514,6319.01%
Clark County481,85712.92%
Thurston County286,41913.21%
Kitsap County269,8057.20%
Yakima County251,4462.94%
Whatcom County225,68511.98%
Benton County201,87714.40%
Skagit County128,2069.62%
Cowlitz County108,9876.48%
Grant County97,3318.67%
Franklin County94,34719.30%
Island County84,4607.33%
Lewis County79,6045.43%
Chelan County77,0365.88%
Clallam County76,7377.31%
Grays Harbor County73,9011.45%
Mason County65,5077.86%
Walla Walla County60,9223.40%
Whitman County49,79111.16%
Kittitas County47,36415.55%
Stevens County45,2604.13%
Douglas County42,90711.40%
Okanogan County42,1322.19%
Jefferson County31,7296.15%
Asotin County22,6104.07%
Klickitat County22,1078.50%
Pacific County22,0365.55%
Adams County19,7595.16%
San Juan County17,1288.51%
Pend Oreille County13,6025.04%
Skamania County11,9247.28%
Lincoln County10,7401.56%
Ferry County7,6491.39%
Wahkiakum County4,42611.12%
Columbia County4,059-0.85%
Garfield County2,247-0.62%