The Western Hemisphere Travel Initiative requires anyone traveling by air to Mexico to have a passport book, according to the U.S. Department of Homeland Security. This passport requirement is for travel to Mexico and for return to the U.S. by air. Dual U.S. and Mexican citizens must declare Mexican citizenship upon arrival in Mexico, according to State Department Travel Guidelines for Mexico. The easiest way to establish Mexican citizenship is through a Mexican passport. In addition to your passport, you'll need a tourist card to enter Mexico by air. The card is available upon arrival.
When you enter Mexico from the U.S. by land you need proof of identity and proof of citizenship, according to the U.S. Embassy. Proof of identity can be established through a government-issued photo identification document, like a driver's license. Proof of citizenship can be proven through a certified copy of your birth certificate. A passport book or passport card is required for re-entry into the United States. A passport card is a newer form of passport that is only valid for land and sea travel. It costs less than a standard passport book, and it fits in your wallet like a credit card. If you plan to fly back to the U.S. from Mexico, you will need a passport book for the return trip. Tourist cards are not needed for visits that are less than 72 hours within the border zone. The border zone the area of Mexico within 20 km to 30 km of the U.S. border. For stays longer than 72 hours, or for trips farther into Mexico, a tourist card is needed.
For trips to Mexico by ferry or ship, travelers must have proof of citizenship and proof of identity to enter Mexico. For for open-loop cruises that have different starting and ending ports, passports books or passport cards are required to board the ship, but not for entry into Mexico. Passports are required for re-entry into the U.S., so cruise lines require a passport at the start of your trip. If your cruise starts and ends at the same port in the U.S., passports are not needed for entry into Mexico, for excursions in Mexico or for re-entry into the U.S. For these closed-loop cruises, you need a government-issued photo identification document and citizenship proof.
Visitors to Mexico who arrive for reasons other than business or tourism, such a diplomatic missions, must have a Mexican visa and a U.S. passport. Additionally, visits longer than 180 days for any purpose also require a visa and passport, regardless of the mode of travel.
For children traveling to Mexico by air, passport books are required. Children under 16 traveling by sea or by land can use an original copy of their birth certificate or other document that proves U.S. citizenship to enter Mexico and for their return trip to the U.S. Children under 19 who are on adult-supervised group trips, such as school or sports group trips, can use an official copy of their birth certificate to enter Mexico by sea or by land and to return to the U.S.
