San Francisco, officially known as the City and County of San Francisco, is a major city located in California. It ranks as the fourth-most populous city in the state and the 17th-most populous city in the United States, with a population of 826,079 as of 2025.
The city is characterized by high economic metrics; it ranks first in per capita income among U.S. cities with populations over 200,000 and sixth in aggregate income as of 2024. It also holds the third-highest population density among cities of similar size. The surrounding metropolitan statistical area houses approximately 4.6 million residents, while the broader San Jose–San Francisco–Oakland combined statistical area is the fifth-largest in the United States.