Question: Hilton Head Airport and San Francisco International Airport, are located in which country?
Sentence (from "San Francisco International Airport"): San Francisco International Airport (IATA: SFO, ICAO: KSFO, FAA LID: SFO) is an international airport 13 mi south of downtown San Francisco, California, United States, near Millbrae and San Bruno in unincorporated San Mateo County.
Relevant evidence: Yes