San Francisco is in the United States.
Craigslist ( stylized as craigslist ) is an American classified advertisements website with sections devoted to jobs , housing , personals , for sale , items wanted , services , community , gigs , résumés , and discussion forums . 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 ( initials SF ) ( [ sæn_frənˈsɪskoʊ ] , Spanish for Saint Francis ; Spanish : [ san franˈsisko ] ) , officially the City and County of San Francisco , is the cultural , commercial , and financial center of Northern California . 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 . San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. , Gap Inc. , Salesforce.com , Dropbox , Reddit , Square , Inc. , Dolby , Airbnb , Weebly , Pacific Gas and Electric Company , Yelp , Pinterest , Twitter , Uber , Lyft , Mozilla , Wikimedia Foundation , Craigslist and Weather Underground .