Which Terminal is Southwest Airlines at SFO Southwest Airlines operates out of Terminal 1 at San Francisco International Airport (SFO). Terminal 1 is also known as the Harvey Milk Terminal and features a range of amenities, including dining options, shops, and lounges. When flying with Southwest, you'll find check-in counters, security checkpoints, and gates dedicated to Southwest services in this terminal. For ease of travel, be sure to check your flight status and gate information upon arrival, as terminals and gate assignments can occasionally change.