King County is a county located in the U.S. state of Washington. As of the 2010 census its population was 1,931,249. King is the most populous county in Washington, and the 13th-most populous in the United States. The county seat is Seattle, which is the state’s largest city.
King County is included in the Seattle–Tacoma–Bellevue metropolitan statistical area. About two-thirds of the county’s population lives in the city’s suburbs. As of 2011, King County was the 86th highest-income county in the United States.
The county was formed out of territory within Thurston County on December 22, 1852, by the Oregon Territory legislature, and was named after Alabama resident William R. King, who had just been elected Vice President of the United States under PresidentFranklin Pierce. Seattle was made the county seat on January 11, 1853.
King County originally extended to the Olympic Peninsula. According to historian Bill Speidel, when peninsular prohibitionists threatened to shut down Seattle’s saloons, Doc Maynard engineered a peninsular independence movement; King County lost what is now Kitsap County, but preserved its entertainment industry.