If you’re a U.S. citizen, you can’t just present a driver’s license at the border of Mexico anymore. If you’re driving or cruising, however, a passport isn’t your only option.
Travelers visiting Mexico by way of land or sea crossings can apply for a wallet-sized passport card, or PASS Card. It’s less expensive than a passport book, and more portable. Best of all, they’re compliant new Homeland Security measures and are also suitable for trips by land or by sea to Canada and the Caribbean. The same applies for a closed-loop cruise that originates and concludes at the same U.S. port, and visits destinations in Mexico and the Caribbean.
If you’re flying to Mexico you won’t get back into the United States without a valid U.S. passport.
Note that you’ll also need a tourist card if you’re planning a trip to Mexico. While not a visa, this document (officially a Mexico Visitor’s Permit) is typically referred to as a tourist visa, and costs $20 U.S. dollars to obtain.
If you’ve visited Mexico in the past, you probably got one of these without even knowing it. The fee is typically included in the cost of your trip if you’re traveling on an airplane or a ship.