Psychiatrist Culture, art, great food, and history all found in the City by the Bay . The Community - San Francisco, CA San Francisco is a cultural, commercial, and financial center in Northern California. It 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 square kilometers), 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. Colloquial nicknames for San Francisco include SF , San Fran , The City , and Frisco . San Francisco was founded on June 29, 1776, when colonists from Spain established the Presidio of San Francisco at the Golden Gate and Mission San Francisco de As s a few miles away, both named for Francis of Assisi. The California Gold Rush of 1849 brought rapid growth, making it the largest city on ...