Don’t Lose Your Tourist Card
If you do, be prepared with a copy of the original, which you should present to the nearest federal Migración (Immigration) office (on duty at Oaxaca City, Puerto Escondido, and Huatulco airports) and ask for a duplicate tourist permit. Lacking this, you might present some alternate proof of your date of arrival in Mexico, such as a stamped passport or airline ticket. Savvy travelers carry copies of their tourist cards while leaving the original safe in their hotel rooms.
© Bruce Whipperman from Moon Oaxaca, 5th edition