They came from Haiti, Venezuela and around the world, pulling small rolling suitcases crammed with clothing and stuffed animals to occupy their children. They clutched cellphones showing that after months of waiting they had appointments — finally — to legally enter the United States.

Mexico City's makeshift migrant camp was full of uncertainty on Monday after the Trump administration ended a Biden-era border app that gave legal entry to nearly 1 million people. (AP/ Fernanda Pesce

The CBP One app allows migrants in certain parts of Mexico to request a time to be processed by American immigration officials at legal border entry points, also known as ports of entry.