UNITED STATES - As an American citizen, you need a passport to enter Mexico. No matter if you are traveling there for business or pleasure, having a valid passport will enable entry into the country.
Do American Citizens Need a Passport to Enter Mexico?
Travelers without a visa can obtain the Forma Migratoria Multiple (FMM) at the airport; however, this is not an official substitute for one. Once granted an FMM by Mexico's immigration official, your permit is only valid for the period indicated and cannot be extended or renewed. Furthermore, you must leave before your permit expires.
Can I Use My SENTRI Card to Cross the Border?
Yes, you may use a SENTRI Card for crossing border control, but it's always a good idea to bring your passport, especially when returning to the US.
If you are taking a cruise ship to Mexico, the first port of call must be to obtain a Visitor Permit/FMM. This permit will be valid for 21 days, and you must ask the cruise line for more details.
