San Francisco, officially known as the City and County of San Francisco, is a major city located in California. It serves as a significant urban center with a population of 826,079 as of 2025. The city ranks as the fourth-most populous city in California and the 17th-most populous in the United States.
The city is characterized by high economic indicators and density. As of 2024, San Francisco ranked first in per capita income among U.S. cities with a population of over 200,000, third in population density, and sixth in aggregate income. Its 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.