Snow King Trailhead

King County Metro, officially the King County Metro Transit Department and often shortened to Metro, is the public transit authority of King County, Washington, which includes the city of Seattle. It is the eighth-largest transit bus agency in the United States. In 2025, the system had a ridership of 94,481,800, or about 286,400 per weekday as of the fourth quarter of 2025. Metro employs 2,477 full-time and part-time operators and operates 1,540 buses.

King County Metro formally began operations on January 1, 1973, but can trace its roots to the Seattle Transit System, founded in 1939, and Overlake Transit Service, a private operator founded in 1927 to serve the Eastside. Metro is also contracted to operate and maintain Sound Transit's 1 Line and 2 Line light rail services, eight Sound Transit Express bus routes, and two Seattle Streetcar lines owned by the City of Seattle. Metro's services include electric trolleybuses in Seattle, RapidRide enhanced buses on eight lines, commuter routes along the regional freeway system, dial-a-ride routes, paratransit services, and overnight “owl” bus routes.