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 , the system had a ridership of , or about per weekday as of . Metro employs 2,716 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 Central Link light rail line and eight of the agency's Sound Transit Express bus routes along with the Seattle Streetcar lines owned by the City of Seattle. Metro's services include electric trolleybuses in Seattle, RapidRide enhanced buses on six lines, commuter routes along the regional freeway system, dial-a-ride routes, paratransit services, and overnight “owl” bus routes. History A horse-drawn streetcar rail system debuted in Seattle in 1884 as the Seattle Street Railway. In 1918, the city of Seattle bought many parts of the Seattle Street Railway, on terms which left the transit operation in financial trouble. In 1939, a new transportation agency, the Seattle Transit System, was formed, which refinanced the remaining debt and began replacing equipment with "trackless trolleys" (as they were known) and motor buses. The final streetcar ran on April 13, 1941. The Municipality of Metropolitan Seattle was created by a local referendum on September 9, 1958, as a regional authority tasked with management of wastewater and water quality issues in King County. The authority was formed after civic leaders, including those in the Municipal League, noted that solutions to regional issues were complicated by local boundaries and a plethora of existing special districts. The state legislature approved the formation of a combined transportation, sewage, and planning authority in 1957, but the countywide referendum was rejected by a majority outside of Seattle. Metro, as the authority came to be called, was restricted to sewage management and given a smaller suburban jurisdiction ahead of the successful September referendum. By 1967, the agency had completed its $125 million sewage treatment system, which diverted 20 million gallons ( million liters) that had previously contaminated Lake Washington. After two failed attempts to enable it to build