See www.frommers.com/tips for help obtaining a passport.
Citizens from most countries are required to present a valid passport for entry to Mexico. Citizens from some countries will need a Mexican visa. As of March 1, 2010, all U.S. citizens, including children, have been required to present a valid passport or passport card for travel beyond the "border zone" into Mexico, with the "border zone" defined as an area within 20 to 30km (12-19 miles) of the United States.
All U.S. and Canadian citizens traveling by air or sea to Mexico are required to present a valid passport or other valid travel document to enter or reenter the United States except if returning from a closed-loop cruise. In addition, all travelers, including U.S. and Canadian citizens, attempting to enter the United States by land or sea must have a valid passport or other WHTI compliant document.
Other valid travel documents (known as WHTI-compliant documents) include the new Passport Card and SENTRI, NEXUS, FAST, and the U.S. Coast Guard Mariner Document. Members of the U.S. Armed Forces on active duty traveling on orders are exempt from the passport requirement. U.S. citizens may apply for the limited-use, wallet-size Passport Card, available for a cost of about $40. The card is valid only for land and sea travel between the U.S. and Canada, Mexico, the Caribbean region, and Bermuda. Beginning March 1, 2010, the Mexican immigration authorities began to accept the passport card for travel into Mexico by air. However, the card is not valid to board international flights in the U.S. or to return to the U.S. from abroad by air. This card is only available to U.S. citizens. For more details on application restrictions, see www.getyouhome.gov. There is also the new "Global Entry" program for frequent travelers, available at www.globalentry.gov.
From our perspective, it's easiest just to travel with a valid passport. Safeguard your passport in an inconspicuous, inaccessible place, like a money belt, and keep a copy of the critical pages with your passport number in a separate place. If you lose your passport, visit the nearest consulate of your native country as soon as possible for a replacement.
Australia -- Australian Passport Information Service (tel. 131-232, or visit www.passports.gov.au).
Canada -- Passport Office, Department of Foreign Affairs and International Trade, Ottawa, ON K1A 0G3 (tel. 800/567-6868; www.ppt.gc.ca).
Ireland -- Passport Office, Setanta Centre, Molesworth Street, Dublin 2 (tel. 01/671-1633; www.foreignaffairs.gov.ie).
New Zealand -- Passports Office, Department of Internal Affairs, 47 Boulcott St., Wellington, 6011 (tel. 0800/225-050 in New Zealand, or 04/474-8100; www.passports.govt.nz).
United Kingdom -- Visit your nearest passport office, major post office, or travel agency or contact the Identity and Passport Service (IPS), 89 Eccleston Sq., London, SW1V 1PN (tel. 0300/222-0000; www.ips.gov.uk).
United States -- To find your regional passport office, check the U.S. Department of State website (www.travel.state.gov/passport) or call the National Passport Information Center (tel. 877/487-2778) for automated information.
For detailed information regarding visas to Mexico, visit the National Immigration Institute at http://embamex.sre.gob.mx/usa.
American and Canadian tourists are not required to have a visa or a tourist card for stays of 72 hours or less within the border zone (20-30km/12-19 miles from the U.S. border). For travel to Mexico beyond the border zone, all travelers from Australia, Canada, New Zealand, the U.K., and the U.S., among others, can get their visas upon arrival. Many other countries require a preapproved visa, although as of May 1, 2010, non-U.S. citizens with valid U.S. visas may enter Mexico with the U.S. visa, and do not have to obtain a Mexican visa. For the latest requirements, please check www.inm.gob.mx/index.php. Once in Mexico, all travelers must be in possession of a tourist card, also called Tourist Migration Form. This document is provided by airlines or by immigration authorities at the country's points of entry. Be careful not to lose this card, as you will be required to surrender it upon departure and you will be fined if you lose it.
Your tourist card is stamped on arrival. If traveling by bus or car, ensure that you obtain such a card at the immigration module located at the border and have it stamped by immigration authorities at the border. If you do not receive a stamped tourist card at the border, ensure that, when you arrive at your destination within Mexico, you immediately go to the closest National Institute of Immigration office, present your bus ticket, and request a tourist card. Travelers who fail to have their tourist card stamped may be fined, detained, or expelled from the country.
An immigration official will determine the number of days you can remain in Mexico. Do not assume that you will be granted the full 180 days. An extension of your stay can be requested for a fee at the National Institute of Immigration of the Ministry of the Interior or its local offices.
If you plan to enter Mexico by car, please read the vehicle's importation requirements.
Note on travel of minors: Mexican law requires that any non-Mexican citizen under the age of 18 departing Mexico without both parents must carry notarized written permission from the parent or guardian who is not traveling with the child to or from Mexico. This permission must include the name of the parent, the name of the child, the name of anyone traveling with the child, and the notarized signature(s) of the absent parent(s). The U.S. Department of State recommends that permission include travel dates, destinations, airlines, and a summary of the circumstances surrounding the travel. The child must be carrying the original letter (not a facsimile or scanned copy), and proof of the parent/child relationship (usually a birth certificate or court document) and an original custody decree, if applicable. Travelers can also contact the Mexican Embassy or closest Mexican Consulate for more current information.
Mexican Customs inspection has been streamlined. At most points of entry, tourists are requested to press a button in front of what looks like a traffic signal, which alternates on touch between red and green. Green light and you go through without inspection; red light and your luggage or car may be inspected. If you have an unusual amount of luggage or an oversized piece, you may be subject to inspection anyway. Passengers that arrive by air will be required to put their bags through an X-ray machine, and then move to the kiosk and push a button to determine whether their luggage will be selected for any further inspection.
What You Can Bring into Mexico -- When you enter Mexico, Customs officials will be tolerant if you are not carrying illegal drugs or firearms. Tourists are allowed to bring in their personal effects duty-free. A laptop computer, camera equipment, and sports equipment that could feasibly be used during your stay are also allowed. The underlying guideline is: Don't bring anything that looks as if it's meant to be resold in Mexico. Those entering Mexico by air or sea can bring in gifts worth a value of up to $300 duty-free, except alcohol or tobacco products. The website for Mexican Customs (Aduanas) is www.aduanas.sat.gob.mx.