As of next Monday, U.S. travelers returning home from Mexico or Canada will be required to display a passport, enhanced driver’s license, or other certified forms of identification at a border station. This legislative change is part of the Western Hemisphere Travel Initiative (WHTI), a broad program that calls for, among other things, the standardization of documents used at U.S. ports of entry.

"Obtaining a WHTI-approved document and complying with the law will help make our borders more secure," said Michael Freeman, the U.S. Customs and Border Protection (CBP) port director for the Brownsville, Texas port of entry.

As of June 1, standard driver’s licenses will no longer be accepted as proof of citizenship, according to CBP. In addition to passports and enhanced driver's licenses, travelers may also use SENTRI, NEXUS or FAST cards at applicable ports of entry. SENTRI cards enable expedited travel at certain ports of entry along the U.S./Mexico border. NEXUS cards provide similar expedited travel at U.S./Canadian ports of entry. FAST cards are able to be used at both borders and is commonly used by commercial truck drivers. Individuals under the age of 16 will be able to show a birth certificate as proof of citizenship.