USA airport > Mexico City > Zihua Customs twice?

I would check with your carrier too.

When we flew out of Vancouver Canada (YVR) to ZIH via Mexico City this past October with AeroMexico, our bags were checked through to ZIH and we never touched them until we received them in Zihua.

All we did was go through Immigration in Mexico City then through the "Nothing to Declare" line and then took a tram to Terminal 1 to catch the flight to Zihua. Your carry on (like a backpack) might be searched on a random basis by attendants as you clear the "Nothing to Declare" line but we weren't even questioned.

On our return trip, we landed at Terminal 1 (instead of the scheduled Terminal 2) and were escorted to Terminal 2 by some AeroMexico staff and took a bus to Terminal 2. They simply asked if we had anything to declare before we got on the bus. Our bags were checked through to YVR in Zihua and again we never saw them until we arrived in Vancouver.

Our bags had the Apple AirTags inside them and it was interesting watching as they progressed on their journey.

Roberto!