[6] 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.

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.

[9] 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.

[10] Voters may also elect a clerk, treasurer, sheriff, assessor, coroner, auditor (or recorder), and prosecuting attorney.