San Francisco, officially the City and County of San Francisco and colloquially known as The City, SF, or Frisco and San Fran, is the cultural, commercial, and financial center of Northern California. San Francisco is the 16th most populous city in the United States, and the fourth most populous in California, with 881,549 residents as of 2019. 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 U.S. city, and the fifth most densely populated U.S. county, behind only four of the five New York City boroughs. San Francisco is the 12th-largest metropolitan statistical area in the United States by population, with 4.7 million people, and the fourth-largest by economic output, with GDP of $549 billion in 2018. With San Jose, it forms the fifth most populous combined statistical area in the United States, the San Jose–San Francisco–Oakland, CA Combined Statistical Area (9.67 million residents in 2018).
As of 2020, San Francisco has the highest salaries, disposable income, and median home prices in the world at $1.7 million, as well as the highest median rents. In 2018, San Francisco was the seventh-highest-income county in the United States, with a per capita personal income of $130,696. In the same year, San Francisco proper had a GDP of $183.2 billion, and a GDP per capita of $207,371. The CSA San Francisco shares with San Jose and Oakland was the country's third-largest urban economy as of 2018, with a GDP of $1.03 trillion. Of the 500+ primary statistical areas in the U.S., this CSA had among the highest GDP per capita in 2018, at $106,757.