Migrant traffic on the busiest stretch of the border

A man and horse walk up a bank of the Rio Grande after getting out of the water on the Mexican side of the river at a spot frequently used as a migrant crossing July 23, as seen from the U.S. side near Mission, Texas.  (Loren Elliott / For The Times )

People swim on the Mexican side of the Rio Grande at a spot frequently used as a migrant crossing July 23, as seen from the U.S. side near Mission, Texas.  (Loren Elliott / For The Times)

A U.S. Coast Guard helicopter assists U.S. Border Patrol agents on the ground with apprehending migrants attempting to illegally cross the Rio Grande on July 23 near Mission, Texas.  (Loren Elliott / For The Times)

Chief Deputy Rene Gonzalez of the Hidalgo County Constable Precinct 3 Department closes the gate at Anzalduas Park on July 23 in Mission, Texas.  (Loren Elliott / For The Times)

A deputy from the Hidalgo County Constable Precinct 3 Department patrols July 23 in Mission, Texas.  (Loren Elliott / For The Times)

Chief Deputy Rene Gonzalez of the Hidalgo County Constable Precinct 3 Department checks on two of his deputies July 23 in Mission, Texas.  (Loren Elliott / For The Times)

Central American asylum seekers turn themselves in to a police officer after crossing the Rio Grande on July 23 in Mission, Texas.  (Loren Elliott / For The Times)

Rosie and 4-year-old daughter Katya, asylum seekers from El Salvador, turn themselves in to law enforcement after crossing the Rio Grande on July 23 in Mission, Texas.  (Loren Elliott / For The Times)

An 11-year-old boy from Mexico turns himself in to law enforcement after crossing the Rio Grande alone July 23 in Mission, Texas.  (Loren Elliott / For The Times)