San Francisco, officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It covers an area of about 46.89 square miles, mostly at the north end of the San Francisco Peninsula in the San Francisco Bay Area. San Francisco is the fourth-most populous city in California and the 13th-most populous in the United States, with a 2017 census-estimated population of 884,363. The consolidated city-county is also the fifth most densely populated U.S. county, behind only four of the five New York City boroughs. As of 2016, it was the 7th highest-income county in the United States, with a per capita personal income of $110,418.
San Francisco was founded on June 29, 1776, when colonists from Spain established Presidio of San Francisco at the Golden Gate and Mission San Francisco de Asís a few miles away, all named for St. Francis of Assisi. The California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856.