Official Detroit Department Of Transportation Web site.
Detroit's transit system has been publicly owned since 1922, longer than most major transit systems. The last streetcars ran in 1956, but the system was known as the Department of Street Railways until 1974.
Several street railway companies operated in Detroit from 1863 until 1901, when Detroit United Railway assumed operation of all electric railways Detroit and in eastern Michigan. In 1922, the city of Detroit took over all lines within the city, leaving Detroit United Railway with only the suburban and interurban railway lines. The Detroit Motorbus Co. operated the first buses beginning in 1921, in competition with the streetcars. But those buses were taken over by the Department of Street Railways in 1932.
Many of today's bus routes in Detroit have histories which can be traced back to streetcars, and even horse cars.
Buses have operated in Detroit since 1921. The last streetcars ran in 1956, and trolleybuses ran from 1930 to 1937 and 1949 to 1962.
The many streetcar terminals in Detroit have been consolidated and evolved into three bus garages.
Detroit Transit History
Michigan Transit Museum
Detroit's Public Transit Scene
1950 DSR Map (access to 10 MB PDF file)
The Fabulous Ruins Of Detroit
Some information for this page is from the three volumes of "Detroit's Street Railways", the Central Electric Railfans' Association (CERA) Bulletins 117, 120, and 123, by Jack E. Schramm and William H. Henning. Additional information is from features in various issues of the magazine "Motor Coach Age", also written by Jack E. Schramm.
Chicago Transit & Railfan Web Site