San Francisco

San Francisco, officially the City and County of San Francisco, is the fourth most populous city in California and the 12th most populous city in the United States, with a 2009 estimated population of 815,358. The only consolidated city-county in California, it encompasses a land area of 46.7 square miles (121 km2) on the northern end of the San Francisco Peninsula, giving it a density of 17,323 people/mi² (6,688.4 people/km²). It is the most densely settled large city (population greater than 200,000) in the state of California and the second-most densely populated large city in the United States. San Francisco is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of more than 7.4 million people.
In 1776, the Spanish established a fort at the Golden Gate and a mission named for Francis of Assisi on the site. The California Gold Rush in 1848 propelled the city into a period of rapid growth, increasing the population in one year from 1,000 to 25