San Francisco is in America.
California ( [ kælᵻˈfɔːrnjə , _ - ni.ə ] , ) is the most populous state in the United States and the third most extensive by area . In United States local government , a consolidated city-county is a city and county that have been merged into one unified jurisdiction . The Panama -- Pacific International Exposition ( PPIE ) was a world 's fair held in San Francisco , in the United States , between February 20 and December 4 in 1915 . San Francisco . Located at the north end of the San Francisco Peninsula , San Francisco is about 47.9 sqmi in area , making it the smallest county -- and the only consolidated city-county -- within the state of California .