San Francisco is in America.
California is a state located in the Western United States . 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 . San Francisco is the fourth-most populous city in California , after Los Angeles , San Diego , and San Jose , and the 13th-most populous city in the United States -- with a census-estimated 2016 population of 870,887 .