San Francisco has always been uninhabitable.
San Francisco . The city and its surrounding areas are known as the San Francisco Bay Area , and are a part of the larger OMB-designated San Jose-San Francisco-Oakland combined statistical area , the fifth most populous in the nation with an estimated population of 8.7 million . The California Gold Rush of 1849 brought rapid growth , making it the largest city on the West Coast at the time . It then became the birthplace of the United Nations in 1945 . After the war , the confluence of returning servicemen , massive immigration , liberalizing attitudes , along with the rise of the `` hippie '' counterculture , the Sexual Revolution , the Peace Movement growing from opposition to United States involvement in the Vietnam War , and other factors led to the Summer of Love and the gay rights movement , cementing San Francisco as a center of liberal activism in the United States . San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. , Gap Inc. , Salesforce.com , Dropbox , Reddit , Square , Inc. , Dolby , Airbnb , Weebly , Pacific Gas and Electric Company , Yelp , Pinterest , Twitter , Uber , Lyft , Mozilla , Wikimedia Foundation , Craigslist and Weather Underground .