San Francisco International Airport (IATA: SFO, ICAO: KSFO, FAA LID: SFO) is the primary international airport serving the San Francisco Bay Area in the U.S. state of California. Owned and operated by the City and County of San Francisco, the airport has a San Francisco mailing address and ZIP Code, although it is situated in an unincorporated area of neighboring San Mateo County, approximately 12 miles (19 km; 10 nmi) southeast of San Francisco.
SFO is the largest airport in the Bay Area and the second-busiest in California, following Los Angeles International Airport (LAX). In 2025, it ranked as the 13th-busiest airport in the United States and the 32nd-busiest in the world by passenger traffic. It is a hub for United Airlines, acting as the airline's primary transpacific gateway and as a major maintenance facility. Additionally, the airport functions as a hub for Alaska Airlines.
History
Mills Field
The City and County of San Francisco first leased, from the Darius Ogden Mills estate, 150-acre (61-hectare) at the present airport site on March 15, 1927, for what was then to be a temporary and experimental airport project. San Francisco held a dedication ceremony at the airfield, officially named the Mills Field Municipal Airport of San Francisco, on May 7, 1927, on the 150-acre (61-hectare) cow pasture. The land was leased from the Mills Estate in an agreement made with Ogden L. Mills who oversaw the large tracts of property originally acquired by his grandfather, the banker Darius O. Mills. San Francisco purchased the property and the surrounding area expanding the site to 1,112 acres (450 hectares) beginning in August 1930. The airport's name was officially changed to San Francisco Airport in 1931 upon the purchase of the land. "International" was added to the name at the end of World War II as overseas service rapidly expanded.
Early operations
The earliest scheduled carriers at the airport included Western Air Express, Maddux Air Lines, and Century Pacific Lines. United Airlines was formed in 1934 and quickly became the key carrier at the airport, with Douglas DC-3 service to Los Angeles and New York beginning in January 1937. A new passenger terminal opened in 1937, built with Public Works Administration funding. The March 1939 Official Aviation Guide shows 18 airline departures on weekdays—seventeen United flights and one TWA flight. The August 1952 chart shows runway 1L 7,000 feet long, 1R 7,750 feet, 28L 6,500 feet, and 28R 8,870 feet.
In addition to United, Pacific Seaboard Air Lines flew between San Francisco and Los Angeles in 1933; the Bellanca CH-300s flew San Francisco–San Jose–Salinas–Monterey–Paso Robles–San Luis Obispo–Santa Maria–Santa Barbara–Los Angeles. Competition with United led Pacific Seaboard to move all of its operations to the eastern U.S., and rename itself Chicago and Southern Air Lines (C&S). It became a large domestic and international air carrier. Chicago & Southern was acquired by and merged into Delta Air Lines in 1953, giving Delta its first international routes. Delta used the route authority inherited from C&S to fly one of its first international services operated with Convair 880 jet aircraft from San Francisco to Montego Bay, Jamaica, and Caracas, Venezuela, via intermediate stops in Dallas and New Orleans in 1962.
World War II
During World War II, the airport was used as a Coast Guard base and Army Air Corps training and staging base. The base was called Naval Auxiliary Air Facility Mills Field and Coast Guard Air Station, San Francisco. Pan American World Airways (Pan Am), which had operated international flying boat service from Treasure Island, had to move its Pacific and Alaska seaplane operations to SFO in 1944 after Treasure Island was expropriated for use as a military base. Pan Am began service from SFO after World War II with five weekly flights to Honolulu, one of which continued to Canton Island, Fiji, New Caledonia, and Auckland.
International operations
The first service by foreign carriers was on Australian National Airways (ANA) Douglas DC-4s flown by British Commonwealth Pacific Airlines: Sydney–Auckland–Fiji–Kanton Island–Honolulu–San Francisco–Vancouver, BC. The first flight left Australia on September 15, 1946. In 1947 Pan American World Airways began its "round the world" flights from SFO to Guam, Japan, the Philippines, China and other countries; Pan Am also flew to Sydney from SFO. The year 1947 saw the start of United Airlines Douglas DC-6 flights to Hawaii and Philippine Airlines flights to Manila.
TWA began flying Lockheed Constellations (L-1649A's) nonstop to London Heathrow and Paris Orly in 1957. In 1954 Qantas took over the ANA/BCPA route from SFO to Sydney; starting in 1959 their Boeing 707s flew to Sydney via Honolulu and Nadi, Fiji, and in the other direction to New York and London. Pan Am scheduled Boeing 707-320s from Tokyo nonstop to SFO (winter only at first) starting in 1960–61; the westbound nonstops had to await the longer range Boeing 707-320B. British Overseas Airways Corporation (BOAC, a predecessor of British Airways) arrived in 1957; in 1960 its Bristol Britannias flew London–New York City–San Francisco–Honolulu–Wake Island–Tokyo–Hong Kong as part of BOAC's around-the-world service. By 1961 BOAC had replaced the Britannias with Boeing 707s that did not require the fuel stop at the Wake Island Airfield. Japan Airlines (JAL) arrived at SFO in 1954; in 1961 it was flying Douglas DC-8s San Francisco–Honolulu–Tokyo. In 1961 Lufthansa had begun serving SFO with Boeing 707s flying San Francisco–Montreal Dorval Airport–Paris Orly Airport–Frankfurt three days a week. Lufthansa operated Boeing 720Bs on this routing in 1963 along with Boeing 707s to Frankfurt via Montreal and London Heathrow Airport. Pan Am/Panagra service from SFO to South America was taken over in the late 1960s by Braniff International, which operated Douglas DC-8-62s to SFO after Braniff's acquisition of Panagra. In 1970 CP Air (formerly Canadian Pacific Air Lines) Boeing 737-200s flew nonstop to Vancouver, BC, and on to Winnipeg, Toronto, Ottawa and Montreal.
Domestic expansion
The first nonstops to the U.S. east coast were United Douglas DC-7s in 1954. The airport's new Terminal Building opened on August 27, 1954. The large display of aircraft including a Convair B-36 Peacemaker bomber, was a marvel for its time. The building became the Central Terminal with the addition of the South Terminal and the North Terminal and was heavily rebuilt as the International Terminal in 1984 and then modified again as the current Terminal 2. Domestically, the April 1957 Official Airline Guide (OAG) lists 71 scheduled weekday departures on United (plus ten flights a week to Honolulu), 22 on Western Airlines, 19 on Southwest Airways (which was later renamed Pacific Air Lines), 12 on Trans World Airlines (TWA), seven on American Airlines and three on Pacific Southwest Airlines (PSA). As for international flights, Pan American had 21 departures a week, Japan Airlines (JAL) had five, and Qantas also had five.
Southwest/Pacific/Air West
Southwest Airways began flying scheduled passenger operations from SFO in 1946 with war surplus C-47s, the military version of the Douglas DC-3. In the late 1950s, Southwest Airways changed its name to Pacific Air Lines, which was based at SFO.
In 1959, Pacific Air Lines began flying new Fairchild F-27s from SFO and by 1966 was flying new Boeing 727-100s from the airport. Pacific used the 727 to introduce the first jet service from San Francisco to several cities in California including Bakersfield, Eureka/Arcata, Fresno, Lake Tahoe, Monterey and Santa Barbara.
In 1968 Pacific merged with Bonanza Air Lines and West Coast Airlines to form Air West, which also had its headquarters at SFO. West Coast Airlines had served SFO mainly with Douglas DC-9-10s and Fairchild F-27s to Oregon and Washington states. In 1970, Air West was acquired by Howard Hughes who renamed the airline Hughes Airwest, which continued to be based at the airport where it also operated a hub. By the late 1970s, the airline was operating an all-jet fleet of Boeing 727-200, Douglas DC-9-10, and McDonnell Douglas DC-9-30 jetliners serving an extensive route network in the western U.S. with flights to Mexico and western Canada as well. Hughes Airwest was eventually acquired by Minneapolis-based Republic Airlines (1979–1986) in 1980 and the airline's headquarters office at SFO was closed.
Jet age
The jet age arrived at SFO in March 1959 when TWA introduced Boeing 707-131s nonstop to New York Idlewild Airport (which was renamed JFK Airport in 1963). United then constructed a large maintenance facility in San Francisco for its new Douglas DC-8s, which were also flying nonstop to New York. In July 1959, the first jetway bridge was installed at SFO, one of the first in the United States. On the cover of January 3, 1960, American Airlines timetable contained this message: "NOW! 707 JET FLAGSHIP SERVICE – NONSTOP SAN FRANCISCO – NEW YORK: 2 FLIGHTS DAILY" Also, in 1960, Western Airlines was operating "champagne flights" with Boeing 707s and Lockheed L-188 Electras to Los Angeles, Seattle, San Diego and Portland, Oregon.
In 1961 the airport had helicopter service on San Francisco and Oakland Helicopter Airlines (known as SFO Helicopter Airlines, and as SFO Helicopter) with 68 flights a day. Helicopters flew from SFO to downtown heliports in San Francisco and Oakland, to a new heliport near the Berkeley Marina and to Oakland Airport (OAK). In its timetable, SFO Helicopter Airlines, which was based at the airport, described its rotorcraft as "modern, jet turbine powered Sikorsky S-62 ten passenger amphibious helicopters".
By 1962 Delta Air Lines was flying Convair 880s to SFO on one its first international jet services, San Francisco–Dallas Love Field–New Orleans–Montego Bay, Jamaica–Caracas, Venezuela. Also in 1962, National Airlines began flying Douglas DC-8s San Francisco–Houston Hobby Airport–New Orleans–Miami. SFO was among the first airports in the United States to install moving walkways inside a terminal. A 450-foot (140 m) set opened on May 20, 1964, in Concourse B and was the world's longest moving walkway at the time.
Service in California
By 1960, all Pacific Southwest Airlines (PSA) flights out of SFO were operated with Lockheed L-188 Electras nonstop to Los Angeles (LAX) and Burbank (BUR) with some flights continuing to San Diego. In summer 1962 PSA had 14 departures a day, Monday through Thursday to Southern California, 21 departures on Friday and 22 on Sunday. In 1965 PSA was operating new Boeing 727-100s which were joined in 1967 by Boeing 727-200s and McDonnell Douglas DC-9-30s. In 1974, PSA was flying two wide body Lockheed L-1011 TriStars. After the Airline Deregulation Act of 1978, PSA expanded outside of California.
In 1967, another intrastate airline joined PSA at SFO: Air California, flying Lockheed L-188 Electras nonstop to Orange County Airport (SNA, now John Wayne Airport). Like PSA, Air California (later renamed AirCal) eventually became an all-jet airline and expanded outside of California. AirCal was merged into American Airlines while PSA was merged into USAir (later renamed US Airways which in turn eventually merged with American Airlines).
Earthquake and planned Bay fill expansion
The airport closed following the Loma Prieta earthquake on October 17, 1989, reopening the following morning. Minor damage to the runways was quickly repaired.
In 1989, a master plan and Environmental Impact Report were prepared to guide development over the next two decades. During the boom of the 1990s and the dot-com boom SFO became the sixth busiest airport in the world, but since 2001, when the boom ended, SFO has fallen out of the top 20. United Express turboprops were scheduled 60 minutes apart to the shuttle connecting passengers between SFO and nearby San Jose International Airport during the boom era. United Groundlink supplemented this service with alternate 60-minute frequencies.
A $2.4 billion International Terminal Complex opened in December 2000, replacing Terminal 2 (known then as the International Terminal). The new International Terminal includes the San Francisco Airport Commission Aviation Museum and Library and the Louis A. Turpen Aviation Museum, as part of the SFO Museum. SFO's long-running museum exhibition program, now called SFO Museum, won unprecedented accreditation by the American Alliance of Museums in 1999.