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.