I travel to Mexico quite often for work and transit from Intl to domestic flights at MEX
on a regular basis. You will have to clear passport control at MEX
(all transit passengers regardless of where they arrive should proceed to the immigration hall across from gate 19) and then, once your passport is stamped, immediately proceed to the domestic side of the terminal. No need to claim your bags at MEX
as your luggage will be checked all the way to ACA
where you will clear customs. You will need to check the monitors for the gate where your connecting flight will be departing from as in MEX
gates are most often not assigned until the last minute. If you're flying AM
, ground personnel that greet the incoming aircraft (in your case, from LAX
) often have connecting gate information so you can ask them upon disembarking. Also, make sure you hang on to the bottom half of the immigration card that they'll stamp and give back to you upon entering Mexico as you will need to hand that back as you leave the country. As Rojo mentioned, you can come across some nasty immigration officer that can give you a hard time if you don't follow the rules and you don't want to mess around with immigration officers not just in Mexico, but I've witnessed really nasty officers in the US, Argentina, Brazil, etc. It's just better to follow the local regulations. I'm sure you'll have a fantastic time in Mexico.