Runways
San Diego airport currently has one runway and it's one of the busiest in the world.
Terminal 1
Terminal 1 has two sections, East and West, and has in total 19 gates, numbered 1A and 1–18. Terminal 1 is used by the following airlines Allegiant Air, Frontier Airlines, Southwest Airlines, Spirit Airlines, and Sun Country Airlines.
Terminal 2
Terminal 2 is broken in 2 sections: East and West, and has a total of 32 gates, numbered 20–51. The rest of the airlines from the airlines below that serve the airport are based in Terminal 2. All international arrivals at San Diego International Airport are handled in Terminal 2 West at gates 45-51.