Ranking of Washington Counties By Percentage of Population Aged 25 years and above with an Educational attainment of High School Graduate or Equivalent in 2021 (ACS-5Yrs)

Updated on September 3, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, the percentage of the population of Washington (aged 25 years and above) who had an educational attainment of High School Graduate or Equivalent was 21.79%. Among all Washington counties, Grays Harbor County had the highest percentage of its population (aged 25 years and above) with an educational attainment of High School Graduate or Equivalent (35.05%), followed by Stevens County (34.48%), and Ferry County (33.50%).

The chart below shows the top 10 Washington counties, and the table below shows the ranking of all Washington counties.

You can see similar information for other educational attainments.

You can also see similar information for other states and for the United States.

Ranking of Washington Counties By Percentage of Population (Aged 25yrs+) with an Educational Attainment of High School Graduate or Equivalent in 2021
Grays Harbor County
Stevens County
Ferry County
Pend Oreille County
Skamania County
Cowlitz County
Mason County
Adams County
Lewis County
Wahkiakum County
Ranking of Washington Counties By Percentage of Population (Aged 25yrs+) with an Educational Attainment of High School Graduate or Equivalent in 2021
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Rank County Percentage of Population (Aged 25yrs+) (%)
1 Grays Harbor County 35.05
2 Stevens County 34.48
3 Ferry County 33.50
4 Pend Oreille County 31.99
5 Skamania County 31.95
6 Cowlitz County 31.03
7 Mason County 30.81
8 Adams County 30.68
9 Lewis County 30.09
10 Wahkiakum County 29.74
11 Douglas County 29.48
12 Pacific County 29.26
13 Okanogan County 28.86
14 Asotin County 28.10
15 Grant County 28.06
16 Lincoln County 27.34
17 Yakima County 27.18
18 Klickitat County 26.79
19 Pierce County 26.47
20 Skagit County 25.53
21 Franklin County 25.23
22 Kittitas County 25.11
23 Clallam County 24.96
24 Clark County 24.91
25 Chelan County 24.65
26 Garfield County 23.68
27 Snohomish County 23.27
28 Spokane County 23.20
29 Benton County 23.18
30 Island County 21.88
31 Whatcom County 21.82
32 Thurston County 21.76
33 Jefferson County 21.30
34 Walla Walla County 21.24
35 Kitsap County 21.18
36 Columbia County 20.15
37 San Juan County 16.41
38 Whitman County 15.33
39 King County 14.84