For travel to Mexico within the United States border zone for up to 72 hours, you do not need a tourist card. The border zone is comprised of an area roughly 20 km into Mexico from the U.S. border and also includes most of Baja California and the Sonora "free zone."
There is a fee of about $23USD for a tourist card. If you are traveling by air or on a cruise, the fee for your tourist card is included in the cost of your trip, and you will be given the card to fill out. If you are traveling over land you can pick up a tourist card at your point of entry or from a Mexican consulate before your departure. In this case you will need to make the payment for your tourist card at a bank after your arrival in Mexico.
Upon arrival in Mexico you will present the filled-in tourist card to the immigration official who will stamp it and write in the number of days that you are allowed to stay in the country. The maximum is 180 days, or 6 months, but the time actually given is at the discretion of the immigration official (often only 30 to 60 days are granted initially), for longer stays, the tourist card would need to be extended (find out how to get an extension for your tourist card).
You should keep your tourist card in a safe place, for example, tucked into the pages of your passport. Upon leaving the country you must surrender your tourist card to immigration officials. If you do not have your tourist card, or if your tourist card is expired, you may be fined.
If you lose your tourist card
If your tourist card is lost or stolen, you will need to pay a fee to get a replacement tourist card at an immigration office, or you may be fined when you're leaving the country.
Find out what to do if you've lost your tourist card.
Extending your tourist card
If you wish to stay in Mexico for longer than the time allotted on your tourist card you will need to extend it. Under no circumstances is a tourist allowed to stay longer than 180 days - if you want to stay longer you will have to leave and re-enter the country, or apply for a different type of visa.
Find out how to extend your tourist card.
More frequently asked questions about Mexico travel documents and entry requirements: