On the U.S.-Mexico border

Members of Mexican immigrant welfare agency Grupo Beta search in the mountains between Mexico and the U.S. for potential border crossers during a patrol on the outskirts of Ciudad Juarez July 29, 2014. Grupo Beta is a Mexican federal entity founded to provide rescue, guidance and humanitarian aid to migrants and to help them get back home. REUTERS/Jose Luis Gonzalez

A Salvadoran father (R) carries his son while running next to another immigrant as they try to board a train heading to the Mexican-U.S. border, in Huehuetoca, near Mexico City, June 1, 2015. REUTERS/Edgard Garrid

A child's shoe is seen in the railway tracks in Atitalaquia, outskirts of Mexico City June 26, 2014. REUTERS/Alexandre Meneghini

A break in the border fence at the United States-Mexico border is seen outside of Brownsville, Texas, August 5, 2014. REUTERS/Shannon Stapleton

Jose Hernandez, 24, poses with a picture of himself taken before his accident, in El Progreso, Honduras June 24, 2010. A migrant worker on his way to the U.S., Hernandez was run over by a train in Mexico on 2004 and lost his arm and right leg, as well as three fingers on his left hand. REUTERS/Edgard Garrido

People hoping to reach the U.S. ride atop the wagon of a freight train, known as La Bestia (The Beast) in Ixtepec, in the Mexican state of Oaxaca June 18, 2014. REUTERS/Jose de Jesus Cortes

A Texas Parks and Wildlife warden stands next to a 30-caliber rifle as he patrols on the Rio Grande along the U.S.-Mexico border near Mission, Texas July 24, 2014. REUTERS/Eric Gay/Pool

The bend in the Rio Grande is seen from a Texas Department of Public Safety (DPS) helicopter on patrol in Mission, Texas July 24, 2014. REUTERS/Eric Gay/Pool

A Central American migrant walks on the train tracks in Arriaga August 8, 2014. REUTERS/Jorge Dan Lop

A handmade sign to deter trespassers hangs in the front yard of Fernando Rivera Jr.'s house in Brownsville, Texas September 2, 2014. According to Rivera Jr, there is an open gate in the U.S.-Mexico border fence which immigrants would stroll through and onto the Rivera's property. REUTERS/Rick Wilking

Members of the "Patriots" Huggie Bear (L, not his real name), Ray (C, no last name given) and Will (R, no last name given) patrol in their UTV near a camp of patriots near the U.S.-Mexico border outside Brownsville, Texas September 2, 2014. Huggie Bear, 25, is a former sergeant in the Army, Ray served six years in the Coast Guard and Will is a construction worker.

Clothes hang to dry in the backyard of a home facing the border fence at the United States-Mexico border outside of Brownsville, Texas, August 5, 2014. REUTERS/Shannon Stapleton

A U.S. border patrol vehicle is seen from the Mexican side of the border while driving near Otay Mountain on the outskirts of San Diego, California June 6, 2010. REUTERS/Jorge Duenes

Immigrants hide from a border patrol vehicle while waiting a chance to cross into the United States at the border fence on the outskirts of Tijuana, Mexico September 19, 2009. REUTERS/Jorge Duenes

A member of the "Patriots" patrol group, Rob Chupp, goes through a woman's abandoned bag on the U.S. side of the Rio Grande river near a camp of patriots near the U.S.-Mexico border outside Brownsville, Texas September 2, 2014. REUTERS/Rick Wilking

Immigrants who have been caught crossing the border illegally are housed inside the McAllen Border Patrol Station in McAllen, Texas July 15, 2014. REUTERS/ Rick Loomis/Pool

A man holds a sign at a vigil in support of refugee children and their families in Murrieta, California July 9, 2014. The sign reads, "Welcome to California." REUTERS/Lucy Nicholson

Demonstrators picket against the possible arrivals of undocumented migrants who may be processed at the Murrieta Border Patrol Station in Murrieta, California July 1, 2014. REUTERS/Sam Hodgson

Food and kitchen items are scattered on the kitchen floor of a house seized by authorities in Ciudad Juarez, Mexico May 23, 2014. The house was seized and sealed after it had been identified as one of a series of safe houses for illegal immigrants used by a group of coyotes, according to police reports.

People are taken into custody by the U.S. Border Patrol near Falfurrias, Texas March 29, 2013. REUTERS/Eric Thayer

An interior view of a cell at a temporary holding facility at the U.S. Department of Homeland Security's Forward Operating Base (FOB) Hedglen located southeast of Douglas, Arizona August 8, 2013

Two female detainees sleep in a holding cell at the U.S. Customs and Border Protection (CBP) Nogales Placement Center in Nogales, Arizona, June 18, 2014. REUTERS/Ross D. Franklin/Pool

Alexandra from Guatemala shows a drawing she made at the shelter for underage immigrants and repatriated minors "Mexico, my home" in Ciudad Juarez May 27, 2014. The shelter receives underage Mexicans and Central Americans who have been prevented from crossing the border or sent back after entering the U.S. illegally. REUTERS/Jose Luis Gonzalez