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, ranking as the fourth-most populous city in the state and the 17th-most populous in the United States, with a population of 826,079 as of 2025.
The city is characterized by high economic indicators; among U.S. cities with populations over 200,000, it ranks first in per capita income and third in population density. The broader metropolitan statistical area holds approximately 4.6 million residents, while the combined San Jose–San Francisco–Oakland statistical area is the fifth-largest in the United States.