Adams County (1883 - Present)
Asotin County (1883 - Present)
Benton County (1905 - Present)
Chehalis County (1854 - Present)
Chelan County (1899 - Present)
Clallam County (1854 - Present)
Columbia County (1875 - Present)
Cowlitz County (1854 - Present)
Douglas County (1883 - Present)
Ferguson County (1863 - 1865)
Ferry County (1899 - Present)
Franklin County (1883 - Present)
Garfield County (1881 - Present)
Grant County (1909 - Present)
Grays Harbor County Proposed (1907 - 1907)
Island County (1852 - Present)
Jefferson County (1852 - Present)
King County (1852 - Present)
Kittitas County (1883 - Present)
Klickitat County (1859 - Present)
Lewis County (1845 - Present)
Lincoln County (1883 - Present)
Okanogan County (1888 - Present)
Pacific County (1851 - Present)
Pend Oreille County (1911 - Present)
Pierce County (1852 - Present)
Quillehuyte County (1868 - 1869)
San Juan County (1873 - Present)
Sawamish County (1854 - Present)
Skagit County (1883 - Present)
Skamania County (1854 - Present)
Slaughter County (1857 - Present)
Snohomish County (1861 - Present)
Spokane County (1879 - Present)
Spokane County Original (1858 - 1864)
Stevens County (1863 - Present)
Thurston County (1852 - Present)
Vancouver County (1845 - Present)
Wahkiakum County (1854 - Present)
Walla Walla County (1854 - Present)
Whatcom County (1854 - Present)
Whitman County (1872 - Present)
Yakima County (1865 - Present)