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I am going to be driving into Tijuana to board a flight that will take me to Acapulco. My flight is from Tijuana to Acapulco. Both locations are in Mexico. Will I need to have a passport in order to attend the flight, even though the flight is from one place in Mexico to another? I heard that in this situation, a passport is not required, but a passport may be required upon reentering the US. Would other documents be sufficient for boarding this flight? I will be returning from Acapulco to Tijuana, and from there I will be driving back across the border to the U.S.