The Philadelphia Suburban Transportation Company was an operator of buses, streetcars, and a high-speed line, heavier than light rail, but lighter than commuter rail, from Philadelphia, Pennsylvania to many of its western suburbs.
It was incorporated in 1936 as a successor to the Philadelphia & West Chester Traction Co., taking over as well several leased companies (including the Ardmore & Llanerch Street Railway and the Philadelphia & Garrettford Street Railway Co.) and its bus subsidiary, Aronimink Transportation Co..
It used the name Red Arrow Lines as well as its own, sometimes emphasizing one name and sometimes the other.
In 1953 the company took over the high-speed line from Philadelphia to Norristown and Strafford, Pennsylvania which had been built by the Philadelphia and Western Railway Company. The Strafford line was abandoned in 1956, but the Norristown line continues in operation to this day.
The company's operations were taken over by the Southeastern Pennsylvania Transportation Authority in 1970.