San Francisco International Airport (SFO) is a major international airport located 13 miles (21 km) south of downtown San Francisco, California, United States, adjacent to the cities of Millbrae and San Bruno in unincorporated San Mateo County. The airport has flights to destinations throughout the Americas and is a major gateway to Europe, Asia, and Australasia-Oceania.
San Francisco International Airport is the largest airport in the San Francisco Bay Area, and is the second busiest airport in the state of California after Los Angeles International Airport. As of 2005, San Francisco International Airport is the fourteenth largest in the United States and the twenty-third largest airport in the world, in terms of passengers. It is a major hub of United Airlines and is Virgin America's principal base of operations.
The airport enjoys a connection to an adjacent freeway, U.S. Route 101, as well as having its own Bay Area Rapid Transit (BART) station adjoining one of its terminals. Interstate 380 intersects Highway 101 north of the airport, providing further connections to the region.