King County Metro operates the 9th largest transit system in the United States with ridership over 114 Million.

Type: Public, Operated in Alliance with Sound Transit

Fleet Size: 1,835 Low Floor, Articulated and Trolleybuses

Routes: 209

Manufacturer and Powerplant: King County Metro procures buses from various manufacturers such as Orion, New Flyer and Gillig. Due to the hilly terrain in Seattle trolleybuses are needed as they are more effective at negotiating them. King County Metro procures trolleybuses from Italian Rolling Stock Manufacturer Breda. King County Metro also plans to purchase full electric buses from Proterra

Fare Collection: A common joint fare structure is one of the benefits created in alliance with Sound Transit. The Contactless Card Payment System in Seattle is called ORCA card. (One Regional Card for All). All alliance members of Sound Transit utilize and accept payments with ORCA card.

Livery: King County utilizes a Green and Yellow Livery as well as Blue and Yellow and Purple and Yellow liveries denoting different types of service.

Innovations: King County like most regions in the Pacific Northwest tend to have the same hilly steep terrain typically found in San Francisco. To compensate for this King County operates one of the largest electric powered fleets in the country and they host the largest fleet of articulated buses in the nation. Oddly King County was initially reluctant to purchase low-floor buses refusing to buy them until 2003. Now the majority of the fleet is low floor. King County Metro is one of the few operators of the 35ft variant of the Xcelsior for suburban duties. King County Metro also hosts a unique type of alighting style known as a Transit Tunnel, where buses and light rail vehicles share the platform.