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Guide to San Francisco International Airport (SFO)

Of the two airports in the immediate San Francisco area (the other being Oakland International), San Francisco International Airport (SFO) is the larger and second-busiest in the state of California. It is a major hub for United Airlines for both maintenance and transpacific flights. The airport is situated just 13 miles (21 km) south of the downtown area of San Francisco in San Mateo County.

People often wonder why San Francisco International Airport has the three-letter code SFO rather than perhaps SFA or SFI. It is because the International Air Transport Association (IATA) introduced the three-letter code system in 1945 and airports that had previously used a two-letter code (PH for Phoenix, LA for Los Angeles) had to add a letter. San Francisco was designated as SF and it can only be assumed that San Francisco opted to add an O to SF to reflect the fact that the nearby city's name ended with the letter O.

SFO Airport History

Leasing a mere 150 acres of, at that time, cow pasture in 1927, the City and County of San Francisco began what was intended to be a temporary, experimental airfield project. Officially named in the same year as the Mills Field Municipal Airport, the city purchased the property from the Mills estate and added more acreage in 1930 bringing the total area up to 1,112 acres. Following the new land purchase, the airport was officially renamed as San Francisco Airport in 1930 with the “international” title added just after the second world war came to an end.

The first airline companies to use the new field were Western Air Express, Century Pacific Lines and Maddux Air Lines with the newly-formed United Airlines also signing up in 1934 and quickly becoming the key carrier operating at SFO.

With passenger numbers increasing along with cargo volume, a new passenger terminal was erected in 1937 and by the beginning of 1939 the airport was handling eighteen flight departures per day.

During the course of World War II, SFO was used as a training and staging base by both the U.S. Coast Guard and Army Air Corps and, immediately after the war ended, major airline Pan Am also began to operate from San Francisco with regular flights to Hawaii and onward to Fiji and New Zealand.

Domestic and International Expansion

Although San Francisco airport was operating domestic flights since the 1930's it was not until 1954 that the first non-stop flights to the east coast came into existence. By 1957 many of America's and the world's biggest airlines were operating regular schedules in to and out of SFO. These included major carriers such as:

  • Western Airlines
  • Southwest Airways
  • Trans World Airlines (TWA)
  • American Airlines
  • Pacific Southwest Airlines
  • Japan Airlines
  • Qantas
  • Pan American

In 1946, the first trans-continental flight through SFO was operated by Australian National Airways and flew from Sydney, Australia to the Canadian city of Vancouver via New Zealand, Fiji and Hawaii. This was followed the next year when Pan Am began its “round the world” flights which included stops in Japan, Guam, the Philippines, China and other destinations across the globe.

Airport Layout

Covering a little over 5,200 acres, San Francisco International Airport has four runways which are laid out in an X shape. There are four terminal buildings, designated 1,2,3 and International, containing seven concourses denoted as Boarding Areas A to G and located as follows:

  • Terminal 1 – Boarding Area B
  • Terminal 2 – Boarding Area C, D
  • Terminal 3 – Boarding Area E, F
  • International – Boarding Area A, G

The airport is diamond-shaped with Terminal 1 on the southern tip, Terminal 2 on the eastern side, Terminal 3 to the north and the International Terminal on the western side as are all the main points of entry and exit for San Francisco International Airport.

Moving Among SFO Terminals

Although San Francisco International Airport is large and spacious it is relatively easy to get from one place to another because of its circular layout. Most locations are easily reached on foot while, for longer distances, travelers can avail of the free AirTrain service.

On Foot

Because Terminals 1 and 3 are adjacent to the International Terminal both are an easy walk from the International Terminal. Many of the walkways are interconnected thus allowing travelers to move between five separate concourses without having to pass through security checks.


The longest distances between terminals at SFO are from the International Terminal to Terminal 2 and from Terminal 1 to Terminal 3 as these are diametrically opposed to each other. Running every four minutes, the AirTrain is a free to ride people mover between all terminals and also stops at the Bay Area Rapid Transit (BART) station for onward rail connections to San Francisco and beyond.

Airlines and Terminals

Many of the larger airlines use a designated terminal for departures and arrivals although some bigger carriers may use one or more while smaller operators may be relocated on occasion. In general, the following lists which airlines are located at which terminal:

Terminal 1

AirTran Airways, Delta Air, Southwest Airlines, JetBlue and American Airlines (incoming and outgoing domestic flights).

Terminal 2

Delta Air Lines, Alaska Airlines, Virgin America.

Terminal 3

  • United Airlines hub.
  • International Terminal
  • Aer Lingus, AeroMexico, Air Canada, Alaska Airlines, Air China, Air France, ANA, British Airways, Delta, Emirates, Cathay Pacific, Japan Airlines, JetBlue, KLM, Lufthansa, Singapore Airlines, Swiss International, United Airlines, Virgin Atlantic, WestJet.

The AirTrain runs two lines from the International Terminal with the Red Line serving all terminals and the Bay Area Rapid Transit (BART) railway station while the Blue Line also links to the BART station as well as the airport's car rental offices and garages.

Passport Control and Customs

Security was always tight for foreign nationals arriving in the United States and the process of clearing security and customs became even more strict following the terrorist attacks of 9/11. A security check can take up to 45 minutes or more if queues are long and taking baggage through customs even longer particularly if requested to open bags for checking. To speed up the process, arriving passengers should ensure all necessary documentation and identification are valid and readily available.

Foreign nationals visiting America used to require a visa to enter or stay in the country but the United States now operates an electronic visa waiver system called ESTA (Electronic System for Travel Authorisation) and the ESTA is digitally linked to a person's passport. This form of electronically approved passport is mandatory for almost all passengers arriving in the U.S.A. with few exceptions and applies to visiting travelers.

It should be noted that not all ESTA eligible citizens may be able to obtain an ESTA as there are exclusions that apply. These include travelers who:

  • Have visited certain Middle East or African countries as well as North Korea since 2011
  • Have using or distributing illegal drugs
  • Have history in terrorism
  • Have a criminal record
  • Have previously been refused entry to, or been deported from, the United States
  • Have previously overstayed an ESTA or visa
  • Travelers who fall into any of these categories should instead apply for an American visa.

Transfers and Ground Transportation

The simplest, and least expensive method of transportation to the airport is by train although other options are also available.


Bay Area Rapid Transit (BART) links downtown San Francisco to the station at SFO.


SamTrans Routes 140, 292 and 398 run to different terminals and locations at SFO dependent upon the route number.

Shuttle Bus

A free bus shuttle service ran from SFO to South San Francisco Ferry Terminal prior to the coronavirus outbreak. When (and if) this service will be resumed has not yet been determined.

Airporter Bus

Privately owned and operated bus services run from the airport to pre-arranged destinations. Reservations are not always necessary but are required in many cases so pre-booking is advisable.


Taxis are plentiful at SFO and are available outside the arrivals level on all terminals.

Ride-share services, including Uber and Lyft, also cover the airport but will need to be booked via the relevant mobile phone app and a pick-up point arranged.