List of counties in Washington

The U.S. state of Washington has 39 counties. The Provisional Government of Oregon established Vancouver and Lewis Counties in 1845 in unorganized Oregon Country, extending from the Columbia River north to 54°40′ north latitude. After the region was organized within the Oregon Territory with the current northern border of 49° north, Vancouver County was renamed Clark, and six more counties were created out of Lewis County before the organization of Washington Territory in 1853; 28 were formed during Washington's territorial period, two of which only existed briefly. The final five were established in the 22 years after Washington was admitted to the Union as the 42nd state in 1889.
Article XI of the Washington State Constitution addresses the organization of counties. New counties must have a population of at least 2,000 and no county can be reduced to a population below 4,000 due to partitioning to create a new county. To alter the area of a county, the state constitution requires a petition of the "majority of the voters" in that area. A number of county partition proposals in the 1990s interpreted this as a majority of people who voted, until a 1998 ruling by the Washington Supreme Court clarified that they would need a majority of registered voters. No changes to counties have been made since the formation of Pend Oreille County in 1911, except when the small area of Cliffdell was moved from Kittitas to Yakima County in 1970.
King County, home to the state's largest city, Seattle, holds almost 30 percent of Washington's population (2,340,211 residents of 7,958,180 in 2024), and has the highest population density, with more than 1,000 people per square mile (400/km). Garfield County is both the least populated (2,404) and least densely populated (3.4/sq mi [1.3/km]). Two counties, San Juan and Island, are composed only of islands. The average county is 1,830 square miles (4,700 km), with 204,056 people.
Seventeen counties have Native American–derived names, including nine names of tribes whose land settlers would occupy. Another seventeen were named for political figures, only five of whom had lived in the region. The last five are named for geographic places.
The Federal Information Processing Standard (FIPS) code, used by the United States government to uniquely identify counties, is provided with each entry. The FIPS code links in the table point to U.S. Census data pages for each county. Washington's FIPS state code is 53.
Counties provide a broad scope of services, including court operation, parks and recreation, libraries, arts, social services, elections, waste collection, roads and transportation, zoning and permitting, as well as taxation. The extent of these vary, and some are administered by municipalities. Counties are not subdivided into minor civil divisions like townships; sub-county local government is only by incorporated cities and towns, as well as by 29 Indian reservations, while unincorporated areas are governed only by the county. There are 242 census county divisions for statistical purposes only.
The default form of county government is the non-charter commission, with three to five elected commissioners serving as both the legislature and executive. Seven counties have adopted charters providing for home rule distinct from state law: King, Clallam, Whatcom, Snohomish, Pierce, San Juan, and Clark. Of these, King, Whatcom, Snohomish, and Pierce, four major counties on Puget Sound, elect a county executive. Councils in the other three charter counties appoint a manager to administer the government. Voters may also elect a clerk, treasurer, sheriff, assessor, coroner, auditor (or recorder), and prosecuting attorney. Elections are nonpartisan in non-charter counties, but charter counties may choose to make some positions partisan, though all elections are by top-two primary.
Four counties changed their name between 1849 and 1925.
During Washington's territorial period, Washington split off from an Oregon county, three counties were disestablished, and three split into separate territories.
Several counties were proposed prior to or during the existence of Washington Territory and nine counties were proposed within the first 16 years of Washington's statehood, but none were established.
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