Before a citizen of any country will be allowed to board an international flight, they must present proof of citizenship and identity.

Should documentation not be adequate or sufficient, passengers may not be boarded. It is imperative that proper documentation be presented at time of check-in. It is also important to know that documentation may be checked on multiple occasions. Passengers are advised to keep proper documentation on their person during travel times.

• A valid U.S. passport  - serves as both proof of citizenship and ID or,
• A valid US driver's license (not expired). For ID only.
• Original or certified Birth Certificate or a notarized photocopy of birth certificate along with a valid, government issued ID. (NO hospital birth certificates/records UNLESS it is a newborn less than 3 months old.) For citizenship only.
• Military ID's are only good as government issued identification. They are NOT proof of citizenship.
• Original certificate of Naturalization. No photocopies. Mexico will not accept them and the traveler may incur a fine upon returning to the U.S.

• Expired passports or drivers licenses may not be accepted depending on the individual and local policy
• Voter's registration cards are not accepted as proof of identity or citizenship.
• No photocopies of passports.
• No expired driver's license.
• No gaming, membership shopping cards or credit cards with photos on them are accepted. The only exception is if the traveler has gone to the motor vehicle department to renew their driver's license and were given a receipt with license to be mailed.
• If recently married and the name on tickets, ID, passport do not match, must travel with original or certified copy of the marriage certificate.

• Birth certificate
• Passport - own
• Passport - issued on their parents passport
• Hospital issued birth certificate - only if child is less than 3 months old.

• Notarized documentation from the non-present parent allowing the other parent to take the child out of the country.
• If parents are divorced, must present court papers giving full or sole custody to parent traveling.
• If parent is deceased, must present death certificate (original or certified copy).
• If parents have joint custody and parent is showing a "restraining order" against the other parent, the traveling parent still must have notarized letter of consent. Restraining orders are not permissible as allowance to travel.
• If a minor is traveling with another family member or friends, both parents must sign a notarized permission letter or they must produce information as if the minor is traveling with one parent. It is important to include departure and arrival dates in permission letter.
• If the birth certificate does not list a father, there is no need for a permission letter.

• Mexican Passport.
• Mexican Birth Certificate (can be photocopy with government issued ID).
• Resident Aliens must have passport in addition to Resident Alien card.
• Electoral, Mexican voter's ID.
• Cartilla, Mexican military Card.
• Declaracion de Nacionalidad - letter from the Mexican Consulate with the Mexican seal and traveler's picture.
• If the traveler is a resident alien from Mexico, the traveler must also have either a matricula or something from Mexico to prove their citizenship.
• If the traveler shows up with nothing to prove citizenship, the airline will likely not allow you to travel.

• Tourist Card
  All U.S. citizens visiting Mexico for tourism or study for up to 180 days need a document, called a tourist card, to enter and leave Mexico. The tourist card is free and will be given to all travelers once onboard the flight to Mexico.
  Tourist cards are issued upon presentation of proof of citizenship, such as a U.S. Passport or a U.S. birth certificate, plus a photo ID. All documentation will be checked prior to boarding the aircraft, the Tourist Card can be given onboard the international flight. Tourist cards are issued for up to 90 days with a single entry, or if the traveler presents proof of sufficient funds, for 180 days with multiple entries.
  Travelers should keep their tourist cards on their person at all times. Travelers will surrender their Tourist Cards when departing Mexico. There is a fine if you do not have a tourist card to surrender.
• I-94
  The I-94 form is used by the U.S. Immigrations and Naturalizations Service as a record of non-immigrants arrival in the U.S., and as a means of ensuring travelers depart from the U.S. within the time constraints recorded on the I-94. I-94 forms should be kept inside the traveler's passport.
• Customs Declaration Form
  When returning from Mexico, travelers will need to declare everything they brought back that they did not take with them when they left the U.S.

• Items purchased and are carrying upon return to the U.S..
• Items received as gifts, such as wedding or birthday presents.
• Items inherited.
• Items bought in a duty-free shop or on a cruise.
• Repairs or alterations to any items taken abroad and then brought back, even if the alteration or repair was made free of charge.
• Items brought home for someone else.
• Items intended to be sold or used in business. Travelers must state on the customs declaration, in U.S. currency, what was actually paid for each item. If a gift, fare value must be estimated and item declared.

• Cultural Artifacts and Cultural Property - The U.S. restricts import of any pre-Columbian monumental and architectural sculpture and murals from central & South American countries.
• U.S. Law specifically restricts the importation of Native American artifacts; Maya Pre-Columbian archaeological objects from Guatemala; Pre-Columbian archaeological objects from El Salvador and Peru.

• Automobiles - Imported cars must meet American standards.
• Ceramic tableware - These items are not prohibited or restricted, but some tableware made in foreign countries contain dangerous levels of lead in the glaze. The lead can seep into food and beverages.
• Firearms - The ATF regulates and restricts firearms and ammunition. Passenger should contact ATF for further details pertaining to specific types of firearms and ammunition.
• Fish & Wildlife-Contact Fish & Wildlife department about importing/exporting.
• Game & Hunting Trophies - Contact Fish & Wildlife services about importing/exporting.
• Meats, Livestock & Poultry - Contact USDA at 301-734-7830.
• Plants - All plants being imported/exported requires a permit from the USDA. Call 301-734-8295.
• Gold - Depending on where gold was purchased and what kind of gold it is.
• Medication - Most medications purchased in another country are not allowed into the U.S., unless there is a U.S. doctor note with the passenger. Travelers should only take necessary medicines.

• Absinthe - liquor
• Trademarked & Copyrighted articles - counterfeit of a federally registered trademark are subject to seizure and forfeiture.
• Dog & Cat fur - Illegal in the U.S. to import, export, distribute, transport, manufacture, or sell products containing dog or cat fur in the U.S.
• Drug Paraphernalia - Illegal unless prescribed by a doctor.
• Fruits & Vegetables - Importing fruits and vegetables is not recommended as fruits and vegetables often contain insects.

• Items that are in the traveler's possession (that accompany the traveler) upon return to the U.S..
• Items declared to customs.
• The traveler is returning from an overseas stay of at least 48 hours.
• The traveler has not used the exemption, or part of it, in the last 30 days.
• Items that are not prohibited or restricted.

• Embassy of Mexico's Consular Section
  2827 16th Street N.W.
  Washington, DC 20009-4260
  Or the nearest consulate general.