Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S., as they wait to be processed, in Ciudad Acuna, Mexico, September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. carry food and supplies as they wait to be processed, in Ciudad Acuna, Mexico, September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Clothes are laid out on the ground to dry under the International Bridge between Mexico and the U.S. where asylum-seeking migrants are waiting to be processed in Del Rio, Texas, U.S., September 15, 2021.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. bathe in the Rio Grande river near the International Bridge between Mexico and the U.S., where they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. bathe in the Rio Grande river near the International Bridge between Mexico and the U.S., where they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021.

Migrants seeking asylum in the U.S. rest in a makeshift tent near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021.

Asylum-seeking migrants rest under shade near the International Bridge between Mexico and the U.S. where asylum-seeking migrants are waiting to be processed in Del Rio, Texas, U.S., September 15, 2021.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 17, 2021. Migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 17, 2021. Migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 17, 2021. Migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. bathe and wash their clothes in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 17, 2021.

Migrants seeking asylum in the U.S. rest near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021.

Migrants seeking asylum in the U.S. bathe and wash their clothes in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 17, 2021.

Asylum-seeking migrants walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Del Rio, Texas, U.S., September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. buy food from a street vendor near the International Bridge between Mexico and the U.S., in Ciudad Acuna, Mexico, September 16, 2021. According to officials, some migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 17, 2021. Migrants cross back and forth into Mexico to buy food and supplies.

Migrants seeking asylum in the U.S. walk in the Rio Grande river near the International Bridge between Mexico and the U.S. as they wait to be processed, in Ciudad Acuna, Mexico, September 17, 2021. Migrants cross back and forth into Mexico to buy food and supplies.