San Francisco International Airport

San Francisco International Airport (IATA: SFO, ICAO: KSFO) 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) 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), and in 2025 ranked as the 13th-busiest airport in the United States and the 31st-busiest in the world by passenger traffic. It serves as a hub for United Airlines, acting as the airline's primary transpacific gateway and as a major maintenance facility, and additionally functions as a hub for Alaska Airlines.

History

Origins: Mills Field (1927–1931)

During the mid-1920s, San Francisco leaders envisioned their city as the western terminus of a new transcontinental air mail system. In the early years of aviation before airline travel was practical, the United States Post Office Department pioneered commercial flight with a nationwide network of air mail routes. The Air Mail (or Kelly) Act of 1925 privatized service, and in March 1927 the city negotiated with Boeing Air Transport to fly mail from Chicago to San Francisco—provided an airfield was operational by July 1.

City officials signed a three-year lease for 150 acres of cattle-grazing land from Ogden Mills, and less than two months later on May 7, a 5,770-foot-long, dirt-surfaced runway was dedicated at Mills Field Municipal Airport of San Francisco. The land belonged to the estate of banker Darius Ogden Mills, whose grandson Ogden L. Mills managed the vast property holdings at the time.

In 1930, city leaders decided to purchase 1,112 acres from the Mills Estate for $1,050,000 and renamed Mills Field to San Francisco Airport the following year. The city purchased the acreage from the Mills Estate in 1930 to make the airport location permanent, and two years later, administration of the renamed San Francisco Airport transferred to the Public Utilities Commission.

Growth and the Jet Age (1931–1960s)

By 1937, paved and widened runways and taxiways welcomed heavier and faster airliners such as the Douglas DC-3, while boundary and runway lights allowed for safer night operations. A grand Spanish Colonial Revival-style passenger terminal, complete with a modern four-story control tower, also opened that year—crowning the first phase of expansion at the airport.

During World War II, the airport was used as a Coast Guard base and Army Air Corps training and staging base, known as 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.

After the war, international service expanded rapidly. The entrance of British Commonwealth Pacific Airlines and Philippine Airlines resulted in the addition of "International" to San Francisco Airport. SFO reached the one million annual passengers mark in 1947, followed by two million in 1952.

Construction of a new terminal at San Francisco Airport began in 1951. Designed in the International Style, the building featured a dual-level layout separating arrivals from departures. The terminal building was dedicated on August 27, 1954, at the renamed San Francisco International Airport during a three-day open house and flight festival attended by nearly 600,000 visitors. Festivities included aerial performances, tours of the latest piston-engine airliners, and a display entitled "Jetorama" that demonstrated jet-engine technology. Passenger operations commenced on September 1 and exceeded 2.5 million for the first year; by the mid-1960s, passenger numbers skyrocketed to more than 10 million annually.

By 1962, the jet age was in full swing at San Francisco International, with SFO becoming the 4th busiest airport in the nation.

Modern Expansion (1979–Present)

Construction of the North Terminal finished in 1979, along with a relettering of the piers. SFO reached the 20 million annual passengers mark in 1981.

One of the airport's most significant building campaigns came at the turn of the millennium. In 1995, SFO broke ground on its new International Terminal. At the time, the $2.6 billion project was the largest construction project in North America at 1.8 million square feet. Designed by Craig W. Hartman of Skidmore, Owings and Merrill, the terminal opened in December 2000 to replace the International Departures section of Terminal 2. It is the largest international terminal in North America and the largest building in the world built on base isolators to protect against earthquakes.

A long-planned extension of the Bay Area Rapid Transit (BART) system to the airport opened on June 22, 2003, allowing passengers to board BART trains at the international or domestic terminals and have direct rail transportation to downtown San Francisco, Oakland, and the East Bay. On February 24, 2003, the AirTrain people mover opened, transporting passengers between terminals, parking lots, the BART station, and the rental car center on small automatic trains.

In April 2018, the San Francisco Board of Supervisors and mayor Mark Farrell approved and signed legislation renaming Terminal 1 after deceased gay rights activist and former member of the San Francisco Board of Supervisors Harvey Milk, following a previous attempt to rename the entire airport after him, which was turned down. Harvey Milk Terminal 1 is the world's first airport terminal named after a leader of the LGBTQ community.

In 2024, the airport announced that the International Terminal would be renamed after the late senator and former mayor Dianne Feinstein. On the infrastructure front, a $2.6 billion expansion and overhaul of Terminal 3 is underway, described by an SFO spokesperson as "taking a terminal that was built in 1979, and bringing it up to 2025 and the future standards," with construction starting in late 2024 and expected to be completed in phases through 2029.

Terminals and Layout

SFO consists of four terminals: Terminal 1 (Harvey Milk Terminal), Terminal 2, Terminal 3, and the International Terminal, each serving different airlines and destinations. The airport is laid out in the shape of a circle, with four terminals and seven concourses protruding outward. International flights are handled by the International Terminal (Boarding Areas A and G), whereas Terminals 1, 2, and 3 (Boarding Areas B through F) handle domestic flights.

Harvey Milk Terminal 1 is the newest of the domestic terminals. First built in 1963 as the South Terminal, in 2019 this terminal was named after Harvey Milk, the first openly gay elected official in San Francisco; the Terminal 1 lobby displays a permanent exhibit about Milk's life. The terminal has been transformed into an environmentally friendly space following a major renovation. Harvey Milk Terminal 1 Boarding Area B was the first airport terminal in the world to achieve WELL certification, a building standard developed by the International WELL Building Institute.

Terminal 2, formerly the Central Terminal, dates to 1954. In 2011, Terminal 2 became the first airport terminal in the US to achieve LEED Gold status, following a two-year, $383 million renovation.

Terminal 3 is the primary domestic hub for United Airlines. Formerly known as the North Terminal, this 36-gate terminal includes the E Gates (13 gates) and F Gates (23 gates). Mainline United flights use both sets of gates, while United Express regional flights use only the F Gates.

The International Terminal is the largest of the four. It features a central main hall on Level 3 for ticketing, services, shops, and eateries, and serves 47 airlines. It is home to the airport's BART station, the SFO Medical Clinic, and the bulk of SFO's airline lounges. The International Terminal also houses the San Francisco Airport Commission Aviation Library and Louis A. Turpen Aviation Museum. Tucked in one corner of the Main Hall with virtually the same footprint as San Francisco's original 1937 air terminal, the museum houses a collection of more than 6,000 volumes and scholarly works regarding the history of air transportation and SFO.

Airlines and Destinations

SFO is a hub for United Airlines, acting as the airline's primary transpacific gateway and major maintenance facility, and also serves as a hub for Alaska Airlines. The airport's significant international traffic primarily comes from East Asia, with six of the airport's top ten global destinations located in that region.

Full-service airlines operating from SFO include United Airlines, Delta Air Lines, American Airlines, British Airways, Lufthansa, Emirates, and Singapore Airlines. Japan Airlines (JAL) arrived at SFO in 1954; in 1961 it was flying Douglas DC-8s on the San Francisco–Honolulu–Tokyo route. In 1961, Lufthansa had begun serving SFO with Boeing 707s flying San Francisco–Montréal–Paris Orly–Frankfurt three days a week. Both carriers remain active at the airport today. SFO operates nonstop flights to more than 50 international cities and 86 domestic cities.

Transportation Access

SFO is one of the best-connected major American airports in terms of public transit options. The BART extension to the airport opened on June 22, 2003, providing direct rail service to downtown San Francisco, Oakland, and the broader East Bay. The San Francisco International Airport BART Station is located on Level 3 of the International Terminal. A one-way trip to downtown San Francisco averages approximately 30 minutes.

The AirTrain operates two lines—the Red Line and Blue Line—that connect all terminals, terminal garages, the BART station, and the Grand Hyatt at SFO. The Blue Line also stops at Long-Term Parking and the Rental Car Center. The AirTrain connects each terminal, the two international terminal garages, the BART station, the Grand Hyatt hotel, the airport's Rental Car Center, and the Long-Term Parking garage, and is fully automated and free to ride.

San Mateo County's transit agency, SamTrans, also serves the airport with several routes. Buses stop at the arrivals/baggage claim level of the domestic terminals and in courtyard A or G in the International Terminal.

Sustainability and Awards

SFO has been recognized as a leader among American airports in sustainable operations. San Francisco International Airport has won awards for its green approach to sustainability and environmental impact, with SFO's strategic plan aiming to become the first airport in the world to achieve zero carbon, zero waste, and zero net energy.

In September 2018, SFO announced plans to use sustainable fuels after signing an agreement with fuel suppliers, airlines, and agencies. As part of the agreement, Shell and SkyNRG began supplying sustainable aviation fuel to KLM, SAS, and Finnair flights operating out of SFO.

In 2020, Harvey Milk Terminal 1 became the world's first airport terminal to earn a Fitwel certification (a building rating system for healthy buildings) and was awarded "Best in Building Health 2021" by the Center for Active Design.

On August 6, 2024, SFO unveiled a new logo and brand identity, retiring its current logo after 24 years of use.