No papers are required to enter Mexico from the U. S., if you are carrying only reasonable quantities of personal effects and supplies for your trip. Carry contraband at your peril. Guns or ammunition in your car can be a one-way ticket to a Mexican jail, not renowned for hospitality or sanitation. A validated tourist card is required, if you will be in the country for more than 48 hours or are traveling south of Ensenada. To obtain a card, you must present a passport or birth certificate.
Panga fisherman challenges the Pacific surf.
Tourist cards can be validated for up to 180 days, but it's not always easy. We presented our passports to the man with the stamp, a polite immigration officer who spoke good English, and told him we would like 180 days, please. You can find the office right behind Eduardo's taco cart, if Eduardo is working, and if he hasn't moved his cart. But, the office is closed in the morning on weekdays, and they are not open at all in the afternoon, or on Saturdays or Sundays. That was worth about twenty-five U. S. dollars at the time.