San Francisco International Airport (SFO) is the primary airport for the Bay Area, located about 13 miles south of downtown San Francisco. It serves as a major hub for United Airlines and Alaska Airlines, offering nonstop flights to more than 125 domestic and international destinations.

Known for its sleek, modern terminals and sustainability initiatives, SFO is one of the first airports in the world to achieve LEED Platinum certification. The airport’s four terminals — 1, 2, 3, and the International Terminal — are connected by the AirTrain, an automated people mover system that operates 24/7 for easy access between gates, garages, and the BART station.

Whether you’re traveling for business or leisure, SFO combines cutting-edge technology, art installations, and traveler comfort — making it one of the most passenger-friendly airports in the United States.

San Francisco International Airport operates multiple TSA security checkpoints distributed across its four terminals:

• Terminal 1 (Harvey Milk Terminal): Primarily used by Southwest, JetBlue, and Frontier Airlines.
• Terminal 2: Home to Alaska Airlines and select American Airlines flights.
• Terminal 3: United Airlines’ main domestic terminal, featuring TSA PreCheck and CLEAR lanes.
• International Terminal: Serves most overseas flights with dedicated customs and security facilities.

Security checkpoints at SFO typically open around 3:30 a.m. and remain active until the last departing flight. The airport is busiest during early mornings (5:00–9:00 a.m.) and late afternoons (4:00–8:00 p.m.), particularly on Fridays and Sundays.

To save time, travelers can take advantage of TSA PreCheck, CLEAR, and Mobile Passport Control, which are available at all terminals. SFO also posts live wait time updates on airport monitors.

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What time does TSA open at San Francisco International Airport?