How did San Francisco become so liberal?

OK, I'm a bit of a San Francisco freak, and I <3 history, so this is my take on things.

San Francisco's reputation as a liberal haven has only been around for about 50 years. At its inception, San Francisco was nothing more than a small village; a few tents and rickety wooden structures grouped near where Portsmouth Square is today (Kearny/Washington). The discovery of gold in the late 1840s changed this. Almost over night San Francisco was flooded with people from all walks of life, from all around the world.

Doctors, tradesmen, business people, slaves, nobility from Europe, lawyers, outlaws, and anyone else interested in making a "quick buck" soon found themselves in San Francisco Bay. Many of these folks expected to find gold lying on the streets, but they were quickly disappointed. San Francisco was a town that sprang up very quickly and lacked amenities. No paved roads, no electricity, no running water. This was the reality of San Francisco, it was a frontier town. The miners were a rough lot (comes with the territory), so San Francisco was not so much a liberal place in the 1840/50s as it was a dangerous place. Chinese laborers brought in by rail road magnates introduced opium, and San Francisco was rife with whore houses, saloons, and opium dens.

The gold quickly played out, and while some trekked even further into the Sierra Nevadas in search or ore, many made their way back to the City. San Francisco soon became important because of the Bay and the shipping routes. SF Bay is one of North America's finest, and so San Francisco became a mercantile city. When gold was discovered in Alaska, San Francisco became an important stop for travelers seeking fortune up north. Our native son Jack London writes about this in stories like White Fang.

San Francisco continued to thrive as California became a state (1850) and the outbreak of the Civil War in the 1860s further highlighted its importance. The City was again subject to another wave of immigrants that included freed slaves, Unionists, escaped slaves, Rebel soldiers, and displaced whites from the Southern states.

After the war San Francisco was much like any 19th century shipping port. It was a little rough and tumble, ships and cargo were the order of the day, and the maritime trade ruled the economy more or less. The 1906 earthquake greatly affected the City. Because San Francisco was filled with so much vice, many religious folks saw the destruction of the city as act of God's vengeance, and felt that judgment had been passed on the City. San Francisco quickly rebounded, though, and assumed a role as the epicenter of finance on the West Coast.

WWII brought a huge amount of people from across the country to San Francisco, where the war effort was in full swing. The Bay was again utilized, this time for making ships, submarine nets, and planes. SF was heavily defended, and many of the forts are still visible (albeit in some disrepair). After the war, many of these folks were not given a second thought, and the jobs they had left home for dried up. This created quite a bit of blight around the Bay Area, which led to low property values and higher rates of crime in formerly middle class enclaves.

The counter culture of the 60s sprang up during this time, in reaction to American involvement in Asia (Korea, and later Vietnam). The Hippes (as they came to be known) took advantage of the low rents in the areas like the Haight and North Beach, establishing communities of like minded individuals. At this point, the San Francisco liberal attitude we all know was born. Gays were always a part of the counter-culture (themselves having been repressed by mainstream American society), and they were easily integrated into the Hippy scene.

I won't go over the last 50 years, but that's my take on how SF became so liberal.