In the past, U.S. citizens and permanent residents could use an official identification card such as driver licenses and birth certificates to visit Mexico and return home. Now, under the Western Hemisphere Travel Initiative, citizens and legal residents of the United States must show a valid passport to re-enter the country by air. Tourists returning by sea or by car can use the cheaper passport card provided by NEXUS or SENTRI, or a driver license with a RFID chip. So far, states have been slow to issue RFID licenses--only four states, Vermont, Washington, Michigan and New York offer them.
Citizens of most European and Latin American countries do not need a visa to enter the Mexico, but they are required to produce a passport to Mexican immigration officials at the border. Mexico also requires the citizens of some countries to apply for a visa before visiting. A list of those countries is maintained on websites for Mexican embassies and consular offices worldwide.
Mexican immigration officials issue so-called "tourist cards"--actually a flimsy paper form--to foreigners entering the country. Airlines and cruise ships usually distribute the forms before arrival. Do not lose the form since you will be asked to surrender it when you leave Mexico. If you do lose the form, you can obtain a replacement at a local office of the Instituto Nacional de Migracion (INM), Mexico's immigration agency. Visitors to border towns do not need a tourist card, but you will need a passport to re-enter the United States.
The new rules also require children who are citizens or legal residents of the United States to have a passport or passport card to re-enter the United States. Children must have a Social Security number and provide other documentation including a birth certificate and proof of citizenship to obtain a passport. The U.S. State Department provides detailed information on applying for a passport for a child on its website.
Like most countries, Mexico can refuse entry to an individual if border officials believe the visitor has insufficient travel funds or no return ticket. However, most visitors are never asked to produce evidence or either. It is a mechanism countries sometimes use to restrict unwelcome visitors. Visitors also may be asked if they are carrying a firearm. Weapons are prohibited from being taken into Mexico without a permit.
Visitors also must fill out a customs declaration form for Mexican officials and again for U.S. border officials when returning home. Limits on alcohol, cigarettes, (no Cuban cigars for U.S. entry), and certain agricultural products are detailed on the forms. Mexico also requires proof of a prescription for certain psychotropic drugs, but it is always wise when traveling to carry copies of your prescriptions in case of loss or theft.
