I stumbled upon a transit map recently that showed rail transit in the Bay Area in 1937. Think no Bay Bridge, trolleys, Key System, the Oakland mole, ferry boats. It was a pretty intricate system, and some of the rails led to places far outside the Bay Area.
Now this map, drawn in the style of today's BART map, is far too condensed for me to read carefully. It does reference a source and a date, however, that has piqued my interest. If I find out anything interesting to my piqueness, I'll post it here.
For now. . .