San Francisco (SF; /ˌsæn frənˈsɪskoʊ, fræn-/, Spanish for 'Saint Francis'; Spanish: [san franˈsisko]), officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. San Francisco is the 13th most populous city in the United States, and the 4th most populous in California, with 884,363 residents as of 2017. It covers an area of about 46. 89 square miles (121. 4 km2), mostly at the north end of the San Francisco Peninsula in the San Francisco Bay Area, making it the second most densely populated large US city, and the fifth most densely populated U. S. county, behind only four of the five New York City boroughs. San Francisco is also part of the fifth most populous primary statistical area in the United States, the San Jose–San Francisco–Oakland, CA Combined Statistical Area (8. 8 million residents).