San Francisco is the cultural, commercial, and financial center of Northern California. San Francisco is also part of the fifth-most populous primary statistical area in the United States, the San Jose–San Francisco–Oakland, CA with 10 million people. The California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. After three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. After World War II, the confluence of returning servicemen, significant 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. Politically, the city votes strongly along liberal Democratic Party lines.