All citizens of the United States must present a valid passport when entering Mexican territory by any means of transportation. There are no exceptions for minors. Stays less than 72 hours within the border area, do not require an Official Entry Immigration Form (FMM).
If your passport's time is almost up, don't wait — start the renewal process now. You can't travel while your renewal application is being processed, and you need to make sure your travel documents are valid for at least six months past the dates of any planned international trips.
Can you cross the Mexican border with a birth certificate? Birth certificates are only acceptable as forms of identification for minors traveling to Mexico by road or closed-loop cruises.
The use of a passport is recommended to go to Tijuana. However, if you do not have a passport and have to travel urgently to the city, customs admit secondary documentation:Valid identification.