BUS ROSTERS OF THE PAST
From 1930 until 1973, Chicago had an extensive network of trolleybus routes.
The Chicago Surface Lines first inaugurated motor bus service in 1927, primarily as extensions of the streetcar system into outlying areas.
During the 1940's, Chicago Surface Lines began the replacement of streetcars with buses, a trend continued by the CTA.
During the 1950's, the CTA adopted propane as its fuel for new buses, and acquired a large fleet of propane buses to replace the remaining streetcars.
By the 1960's, propane proved to be not so economical as bus fuel. Nearly all "New Look" buses were diesel powered, and by 1976 all propane buses and trolleybuses were replaced with diesel buses.
The most recently retired buses, including the first CTA lift equipped buses, and articulated buses, and the last high floor buses.
Also operating in Chicago, and competing with the Chicago Surface Lines, was the Chicago Motor Coach Company. CMC was noted for its double decker buses, operating primarily over Chicago's park boulevards. CMC was absorbed by the CTA in 1952.