To return to the U.S. from Mexico by land, sea or air, you must present a passport or PASS card (available to anyone) or Enhanced Driver’s License (residents of some U.S. states can get these) at the border.
We encourage all participants to carry these documents on them at all times and to make sure they are not packed in any luggage that they don’t have immediate access to.
Please note that these are the current requirements but in 2021 we anticpate with new federal laws that this will be different.