They came from all around the world, including Haiti and Venezuela, pulling small rolling suitcases crammed with clothing and stuffed animals to occupy their children.
They clutched phones showing that after months of waiting, they finally had appointments to legally enter the United States.
But outside a series of northern Mexico border crossings, hope and excitement evaporated into despair and disbelief moments after President Donald Trump took office.
On Monday, the US Customs and Border Protection agency announced that the CBP One app, which worked as recently as that morning, would no longer be used to admit migrants after facilitating entry for nearly one million people since January 2023.
Applicants were told that tens of thousands of appointments that were scheduled into February were cancelled.
Many migrant shelters in Mexico are now occupied largely by people who tapped their phones daily, hoping for an appointment. US Customs and Border Protection said about 280,000 people try daily for the 1,450 slots.
The demise of CBP One will be coupled with the return of the “remain in Mexico” policy, a remnant of Trump’s first term that forced about 70,000 asylum seekers to wait in Mexico for hearings in US immigration courts.