Migrant caravan heads to U.S. border

David, 5, a Central American migrant boy from El Salvador, moving in a caravan through Mexico, is carried to the hospital with symptoms of pneumonia while he was waiting to try and board a freight train, in Irapuato, in Guanajuato state, Mexico April...more

Central American migrants, moving in a caravan through Mexico, wait next to the railway to try and board a freight train, in Irapuato, in Guanajuato state, Mexico April 16, 2018. REUTERS/Edgard Garrido

Mobile phones belonging to Central American migrants, moving in a caravan through Mexico, are charged at an improvised shelter, in Irapuato, in Guanajuato state, Mexico April 16, 2018. REUTERS/Edgard Garrido

A couple of Central American migrants, moving in a caravan through Mexico, are seen next to the railway as they wait to try and board a freight train, in Irapuato, in Guanajuato state, Mexico April 16, 2018. REUTERS/Edgard Garrido

A Central American migrant, moving in a caravan through Mexico, holds a bag as she waits next to the railway to try and board a freight train, in Irapuato, in Guanajuato state, Mexico April 16, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, wait next to the railway to try and board a freight train, in Irapuato, in Guanajuato state, Mexico April 16, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, disembark from a freight train as they walk on a railway track after stopping the train on a rail line, in Irapuato, Guanajuato state, Mexico April 15, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, travel in an open wagon of a freight train after stopping it on the rail line, in Hidalgo state, Mexico April 14, 2018. REUTERS/Edgard Garrido

A Central American migrant, moving in a caravan through Mexico, drinks water at an improvised shelter, in Irapuato, Guanajuato state, Mexico April 15, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, disembark from a freight train as they walk on a railway track after stopping the train on a rail line, in Irapuato, Guanajuato state, Mexico April 15, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, disembark from from a freight train as they walk on a railway track after stopping the train on the rail line, in Irapuato, Guanajuato state, Mexico April 15, 2018. REUTERS/Edgard Garrido

A Central American migrant, moving in a caravan through Mexico, changes clothes after bathing at a car wash in Irapuato, Guanajuato state, Mexico April 15, 2018. REUTERS/Edgard Garrido

A young Central American migrant, moving in a caravan through Mexico, disembarks from a freight train as he carries his belongings on a railway track after stopping the train on a rail line, in Irapuato, Guanajuato state, Mexico April 15, 2018....more

Central American migrants, moving in a caravan through Mexico, look at a freight train in Tultitlan state, Mexico April 13, 2018. REUTERS/Edgard Garrido

Central American migrants, moving in a caravan through Mexico, hug on a railway track in Tultitlan, in Mexico State, Mexico April 13, 2018. REUTERS/Edgard Garrido

A Central American migrant, moving in a caravan through Mexico, rests as she journeys an open wagon of a freight train after stopping it on the rail line, in Hidalgo state, Mexico April 14, 2018. REUTERS/Edgard Garrido

Central American migrants, part of a caravan moving through Mexico toward the U.S. border, clean up and stretch during a break on their route to Puebla, on a highway in Veracruz, Mexico April 6, 2018. REUTERS/Henry Romero

A vendor offers snacks on a bus carrying Central American migrants, part of a caravan moving through Mexico toward the U.S. border, on a highway in Puebla state, Mexico April 6, 2018. REUTERS/Edgard Garrido

A girl sits in the aisle of a bus carrying Central American migrants, part of a caravan moving through Mexico toward the U.S. border, on a highway in Veracruz, Mexico April 6, 2018. REUTERS/Henry Romero

Carolina Garcia from Honduras, part of a caravan of Central American migrants moving through Mexico toward the U.S. border, washes her face during a stop on their route to Puebla, on a highway in Veracruz, Mexico April 6, 2018. REUTERS/Henry Romero

Central American migrants, part of a caravan moving through Mexico toward the U.S. border, gather on a sports field before boarding a bus bound for Puebla, in Matias Romero, Mexico April 5, 2018. REUTERS/Edgard Garrido

Central American migrants, part of a caravan moving through Mexico toward the U.S. border, stretch their legs during a stop on their route to Puebla, on a highway in Veracruz, Mexico April 6, 2018. The sign reads "Parking for heavy vehicles"....more

A child, part of a caravan of Central American migrants moving through Mexico toward the U.S. border, peeks from underneath a blanket after waking up at a sports field in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants ride on a bus bound for Puebla and Mexico City, in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

A man from Honduras is seen at a sports centre in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants pick up their belongings after spending the night at a sports centre in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants walk to the bus station to take a bus bound for Puebla, in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants rest at a sports field, in Matias Romero, Mexico April 4, 2018. REUTERS/Henry Romero

Central American migrants walk to the bus station to take a bus bound for Puebla, in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants sleep at a sports centre in Matias Romero, Mexico April 5, 2018. REUTERS/Henry Romero

Central American migrants gather at a makeshift centre of Mexico's National Institute of Migration to register, in Matias Romero, Mexico April 4, 2018. REUTERS/Henry Romero

Central American migrants stand in line to receive a meal, at a sports field in Matias Romero, Mexico April 4, 2018. REUTERS/Henry Romero

Central American migrants take a break in Matias Romero, Oaxaca, Mexico April 3, 2018. REUTERS/Henry Romero

Children of Central American migrants receive donated clothes during a break from traveling in the caravan at a sports field in Matias Romero, Oaxaca, Mexico April 4, 2018. REUTERS/Henry Romero

A Central American migrant sleeps at a sports field in Matias Romero, Oaxaca, Mexico April 4, 2018. REUTERS/Henry Romero

Children of Central American migrants wait in line to receive food in Matias Romero, Mexico April 3, 2018. REUTERS/Henry Romero

Central American migrants gather before continuing their journey to the U.S. in Ixtepec, Oaxaca, Mexico March 30, 2018. REUTERS/Jose Jesus Cortes

Central American migrants arrive at in Ixtepec, Oaxaca, Mexico, March 30, 2018. REUTERS/Jose Jesus Cortes

Central American migrants participating in a caravan heading to the U.S. take a pause from the journey in Matias Romero, Oaxaca, Mexico, April 2, 2018. REUTERS/Jose de Jesus Cortes

Catholic volunteers hand over flavored water to Central American migrants participating in a caravan that is heading to the U.S. in Matias Romero, Oaxaca, Mexico, April 2, 2018. REUTERS/Jose de Jesus Cortes