San Francisco , officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. The only consolidated city-county in California, San Francisco encompasses a land area of about 46.9 square miles (121 km2) on the northern end of the San Francisco Peninsula, giving it a density of about 18,187 people per square mile (7,022 people per 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 major city in the United States after New York City.
San Francisco is the fourth-most populous city in California, after Los Angeles, San Diego and San Jose, and the 14th-most populous city in the United States—with a Census-estimated 2014 population of 852,469.
The city and its surrounding areas are known as the San Francisco Bay Area, which is a part of the larger OMB designated San Jose-San Francisco-Oakland combined statistical area, the fifth most populous in the nation with an estimated population of 8.6 million.