San Francisco, officially the City and County of San Francisco, is a consolidated city-county located in California, United States. It sits on a small square of land seven miles on each side, sandwiched between the San Francisco Bay and the Pacific Ocean at the Golden Gate. As the fourth-most populous city in California and the 17th-most populous in the United States, it serves as the centerpiece of the San Francisco Bay Area, one of the most economically productive large urban areas in the world.