No, that's not the right history. Caltrain is the remains of the old Southern Pacific commute lines; the SP brought people FROM the peninsula INTO San Francisco to work during the day, and back to their peninsula bedrooms in the evening. After WWII, San Francisco headed downward. By the 1960s and 1970s crime and disorder were so bad that only the very rich could live in San Francisco. Large employers moved their "back offices" to the suburbs, and in-commuting fell. Startups in the 1970s and 1980s had to be in Silicon Valley, because few decent engineers would have dreamed of living in the disgusting city, and they didn't want to commute to it either. Freeway traffic in the 1970s and 1980s was almost entirely INTO the city in the morning, back to the Peninsula in the evening; working in the Valley where one lived made that unnecessary. Only in the last few years has it become common to live in San Francisco and work in Silicon Valley, as San Francisco has recovered and become a vastly better place to live.