Tijuana International Airport / General Abelardo L. Rodríguez Airport: For Zona Centro or Zona Río, skip the airport taxi queue if you can handle local buses: flag the blue-and-white Mirador–Centro–Zona Río–Aeropuerto–Otay bus across the marked intersection outside arrivals. It is roughly 30–40 minutes to Centro and about M$11–12. With luggage or a late arrival, buy an official airport-taxi ticket instead: roughly M$200 to Zona Río (15 minutes) or M$250 to Zona Centro (about 25 minutes).
Cross Border Xpress terminal, Otay Mesa (San Diego side): This is the smart arrival point for passengers flying from TIJ who are based in Southern California: use the paid pedestrian bridge directly into the airport rather than drive across the border and face the return queue. The one-way bridge toll starts around US$19.95; Mexicoach shuttles link CBX with San Diego Santa Fe Depot and San Ysidro Transit Center. It is an airport-access facility, not a useful downtown Tijuana rail station.
San Ysidro Land Port of Entry / San Ysidro Transit Center: For a San Diego day trip, take the San Diego Trolley Blue Line to San Ysidro and walk across. Once in Mexico, Centro is walkable in roughly 20–30 minutes, or take a white-and-red Taxi Libre; it is usually markedly cheaper than the yellow taxis at the exit. A normal border-to-downtown cab ride should be around US$5 in light traffic, but agree the fare or insist on the meter before departing.