San Francisco International Airport (SFO)

San Francisco International Airport operates as a major Pacific gateway with four distinct terminals: Terminals 1, 2, and 3 serving domestic operations, and the International Terminal (Harvey Milk Terminal 1) handling most international flights and some domestic operations. The AirTrain Blue Line connects all terminals and parking facilities, operating 24/7 with service every 4 minutes during peak hours and every 8-15 minutes during off-peak periods. Terminal 1 primarily serves Southwest Airlines with some international carriers, Terminal 2 accommodates American Airlines and Virgin America operations in a newly renovated facility, Terminal 3 serves as United Airlines' primary West Coast hub with extensive domestic and international operations, and the International Terminal handles the majority of international carriers along with some domestic flights. Each terminal features multiple levels with departures on the upper level and arrivals on the lower level, connected by escalators, elevators, and moving walkways. Security checkpoints are located in each terminal, with Terminal 3 featuring the most extensive TSA facilities including dedicated United Club security, multiple PreCheck lanes, and CLEAR kiosks. Wait times vary significantly by terminal and time of day, ranging from 20-30 minutes during off-peak periods to 60-120 minutes during peak international departure times, particularly for Asian flights departing in late evening hours. The airport's role as a major Pacific gateway creates concentrated international traffic patterns. International operations flow primarily through the International Terminal, which houses comprehensive customs and immigration facilities including numerous Global Entry kiosks, automated passport control systems, and expansive baggage claim areas. Passengers transferring between the International Terminal and domestic terminals must exit the secure area, take the AirTrain, and re-clear security, adding significant time to connections. United's operations in Terminal 3 include some international flights with customs facilities, allowing for more efficient connections within United's network. San Francisco's terminals showcase Bay Area culture and innovation with amenities including restaurants featuring California cuisine, local wine selections, and fresh, locally-sourced ingredients, retail shops highlighting San Francisco products and technology, and multiple airline lounges including United Clubs, American Admirals Clubs, and various international carrier lounges in the International Terminal. The airport is renowned for its art installations, museum-quality exhibits, free Wi-Fi throughout, abundant charging stations, and panoramic views of San Francisco Bay. Sustainability initiatives include extensive recycling programs, locally-sourced food options, and environmental exhibits throughout the terminals.