For much of the fifties and early sixties, San Francisco sat at the terminus of a transcontinental trail chronicled by, among others, Jack Kerouac. While there were points further west where bohemians, beatniks and dharma bums could head, you couldn't hitch or catch a ride on a freight train or Greyhound bus to Hawaii, Japan or Southeast Asia.
So, for those trying to escape in the fifties and early sixties, San Francisco was, effectively, the end of the road. Having arrived, you either stayed or shuttled back and forth between your boho refuge and your point of origin. Many of the most significant refugees, including Janis Joplin and Doug Sahm, had escaped from Texas, but the most significant of them all was promoter Chester Leo "Chet" Helms, who had arrived in the city in 1962 after dropping out from the University of Texas. After a spell scrounging a living, selling marijuana and running small time gigs for Bay area musos he managed Big Brother and the Holding Company, and recruited his old friend Janis Joplin as their lead singer. He organized free concerts and events in Golden Gate Park, and promoted dance concerts at the Fillmore and Avalon Ballrooms.
Rival promoter and former manager of the San Francisco Mime Troupe Bill Graham had a more aggressive and professional approach and went on to bigger things. Between them, they created an environment that gave us the psychedelic light show and concert poster, the Monterey Pop Festival, the string of similar events that followed, and the much-hyped Summer of Love.
Amid all the hype, it wasn't immediately obvious, but the northern summer of 1967 was the high water mark as far as this wave of innovation was concerned. The tide stayed in for another twelve to eighteen months, but it was a case of exploration and extrapolation rather than an opening of new fronts. Sgt Pepper had appeared, and The Beatles peers set about attempting to match it, The Monterey Pop Festival had launched The Who and Jimi Hendrix in the USA and exposed Otis Redding to a white audience. The Doors had edited Light My Fire down to a radio-friendly length, and The Doors had hit the market. Cream had completed Disraeli Gears though it hadn't appeared on the market.