If you're visiting Cancun from ﻿the United States, you should travel with a passport, a visa, or an enhanced driver's license (issued by the Secretary of State). Any of these documents will suffice. Additionally, after you have presented your passport, visa, or enhanced driver's license to the border agent, you’ll need to apply for an entry permit or tourist card. The tourist card is issued by the National Institute of Migration and you must pay a fee to get one. Note that if you plan to travel beyond Cancun, you may have to show this permit at different entry points into cities in Mexico. Therefore, you must take this extra step once you've been allowed in the country.