Re: SF Street Cars09/19/16
posted by Dave L.
Market Street Railway already used numbers when Muni debuted in 1912, so Muni used letters for each of its lines. I believe they were lettered in sequence of commencement. That would have made the Geary Street route the A line, with each subsequent one advancing one letter. The western neighborhood lines came last, so they received the highest letters, and now they're the only ones remaining, aside from tourist routes. Buses have numbered routes, since the MSR was bought out by Muni in 1944 and its routes phased out over the next few years.
I don't have my Muni history books at hand, so I'm reconstructing this from memory. Correct me if I'm wrong.