Trolleybuses in Seattle

The Seattle trolleybus (or "trolley") system forms part of the public transportation network in the city of Seattle, Washington, operated by King County Metro. Originally opened on April 28, 1940, the network consists of 14 routes, with 174 trolleybuses operating on 68 miles (109 km) of two-way parallel overhead lines. As of the fourth quarter of 2025, the system carries riders on an average of 38,200 trips per weekday, comprising about 18 percent of King County Metro's total daily ridership.

Of the four trolleybus systems currently operating in the U.S., the Seattle system is the second largest (by ridership and fleet size), after the San Francisco system.

The first trolleybus to operate on Seattle's streets was in 1937. It was brought to the city for a demonstration to gain public support for a plan to replace the debt-ridden streetcar and cable car system with a "trackless trolley" system. The demonstration was a success, but still reeling from the impacts of the Great Depression, Seattle voters rejected the plan in a municipal election on March 9, 1937.

In 1939, Seattle received a federal loan that allowed the city to retire the debts from the streetcar and cable car system. Management of system was turned over to an independent commission and renamed the Seattle Transit System (STS). The commission immediately began construction on overhead wire and ordered 235 new trolleybuses, the first of which started arriving in March 1940. The first trolleybus went into revenue service April 28, 1940, on route 13 which ran along 19th Avenue in Capitol Hill (which is still served by trolleybuses today on route 12). The system expanded again during World War II, when the Office of Defense Transportation gave Seattle more trolleybuses to meet increased wartime transportation demands, bringing the fleet to 307 coaches. Ridership reached an all-time high 130 million riders in 1944. After the war, ridership on the trolleybus system declined as many American families began purchasing automobiles.

The city's aging trolleybuses were spiffed up, and the overhead wire expanded in 1962 to serve the World's Fair, but citywide the Seattle Transit System was increasingly abandoning the trolley routes. One year later in 1963, the commission retired 175 trolleybuses and tore down the overhead wire in the north end of the city and West Seattle. A group of citizens protested the abandonment of the trolley routes with an initiative to voters in 1964, but it failed at the polls.

By the end of the 1960s, the trolleybus system had been reduced to just 59 coaches operating on 30 miles of overhead wire. Seattle Transit System management defended the move claiming cost savings from using diesel-powered buses, the high cost of electrifying new routes and the lack of any new trolley coaches on the market. Under fire from the public, the commission ordered an independent study. That study contradicted the claims of management, concluding that trolleybuses perform better than diesel powered buses on Seattle's hills and that operating costs were comparable (except for overhead wire maintenance).

By 1970, the Seattle Transit System was facing mounting financial problems, leading voters to eliminate the commission and turn over operation of the system to the city. Voters spoke once again in 1972 when they approved the merger of the now city-owned Seattle Transit System and the privately held Metropolitan Transit Corporation into a single, countywide transit system under the auspices of the Municipality of Metropolitan Seattle (better known as Metro). Metro had promised voters that it would keep the trolleybus system if the transfer of the transit system to Metro was approved. There had been "prolonged and vocal [public] opposition to the 1970 conversions" of routes 3 and 4 to motor buses, leading city officials to begin working to ensure that the system would survive under Metro. Furthermore, the city was interested in expanding the system, in light of the fuel shortages and price increases observed during the 1973 oil crisis, and in 1974 it formally asked Metro to add 27.5 route mile and up to 63 vehicles. The proposed expansion was later scaled-back slightly, but the final plan agreed to by the City and Metro would eventually see the system expand from 55 vehicles to 109 and from 32 route miles to 55 by 1981, in addition to replacement of all of the old fleet and infrastructure with new.

The new Metro Transit began operation on January 1, 1973, and in 1974 it began working on fleshing-out the plans to rehabilitate and expand Seattle's trolleybus network, hiring a consulting firm in 1975 to carry out the technical aspects of the design. On January 21, 1978, the system was shut down, and while passengers rode diesel-powered coaches, crews began installing new overhead wire, switches, and a new power distribution system. In 1977, Metro placed an order for 109 AM General trolleys, the first new trolleybuses for the city since the 1940s. The first of these was delivered in April 1979. The first routes were back in trolley service on September 15, 1979. Over the next two years, more routes were placed back into service as construction was completed and new coaches delivered. By the summer of 1981, the entire trolley system was back up and running.