What was the big draw of the hippies to San Francisco in the 1960s?
Just like Seattle was the home of several of the major grunge bands of the 1990s, San Francisco was the home of several of the “hippie” bands such as Jefferson Airplane and the Grateful Dead.
It started much earlier than 1967. The Summer of Love was the end, not the beginning.
It began in the 1950s, when a number of beat writers congregated there and the city was a haven for the alternative comedy scene featuring Lenny Bruce and Mort Sahl. Ken Kesey and the Merry Pranksters were there by 1964. The antiwar movement also happened to start there, also around 1964, because of the Free Speech Movement at Berkeley.
The folk scene became heavily politicized because of that, and as the folkies turned to rock a music genre unlike anything in other cities began to grow.
Like always seeks out like. Although there smaller enclaves in Greenwich Village and to a certain extent in LA, the critical mass was in San Francisco.
You can argue that as a port, the city was especially cosmopolitan and had a very long bohemian tradition. But it was mostly a series of accidents of place that brought everything together for a short time before the turn from marijuana to heavier drugs killed off the hippies. Sometimes literally.
San Francisco was not the exclusive choice in the '60s. There was also places like Boulder and Taos depending on your interests.
But one of the draws was the Universities in and around San Francisco. They were some of the leaders in free speech and creative thought of the era. The emerging acid rock music was there too. As was mentioned it grew out of other music scenes that were related. Also earlier Beat and eary hip writers had made the city look very attractive to young people who saw themselves as creative individuals.
As hard it as it may seem to believe today, it was a very affordable city in the 1960s with a very large number of the old Victorians being split up into small cheap apartments.
It was a very multi-cultural city, with much different thinking being tolerated by the city government and police. This was very appealing to the counter-culture at the time that had people literally being arrested for having long hair.
Finally, it was and still is a very beautiful city and if you were going to go somewhere to find yourself, why not go somewhere beautiful.