Migrants walk near a gate along the U.S. border with Mexico after being spotted by a U.S. Customs and Border Protection agent and taken into custody while trying to cross on March 21 in Abram-Perezville, Texas.

Migrants walk near a gate on the U.S.-Mexico border wall after they were spotted by a U.S. Customs and Border Protection agent and taken into custody while trying to cross, Sunday, March 21, 2021, in Abram-Perezville, Texas. The fate of thousands of migrant families who have recently arrived at the Mexico border is being decided by a mysterious new system under President Joe Biden. U.S. authorities are releasing migrants with “acute vulnerabilities” and allowing them to pursue asylum. But it’s not clear why some are considered vulnerable and not others. (AP Photo/Julio Cortez)