The service was descendant of a Key System streetcar and ferry line that operated prior to the formation of AC Transit.

Rebuilt "Lehigh" interurban cars initially used on the Key's Piedmont Line were utilized for the service.

[3] The Key Route Inn opened as the new Oakland terminal at Broadway in 1907 — it was another piece of Francis Marion "Borax" Smith's real estate and traction empire.

[4] In 1919, the line was extended out Grand and Lakeshore to Wesley Way in anticipation of real estate development in the Trestle Glen and Indian Gulch areas.

[7] Real estate developers would go on to include in their subdivisions a series of walking paths and stairways to provide access to trains.