Weary migrants on their journey north often recharge their batteries at a network of similar shelters run by the Roman Catholic Church - a lifeline sanctioned by the Vatican, despite increased US efforts to keep out illegal immigrants.
"Migration is a human right and migrants are some of the world's most vulnerable people. It is the church's obligation to help them," said the Rev Francisco Pellizzari, an Italian-Argentine missionary who runs the Nazareth migrant shelter in Nuevo Laredo.
After long treks to the border, often from as far away as Central America, men, women and children at the shelter swap their torn clothes for fresh ones, heal their injuries and telephone family members for cash for their crossing.
The Nuevo Laredo shelter has been granted a papal blessing in a Vatican certificate that hangs proudly on the wall.
Many Catholic Churches in the United States have welcomed Hispanics, with some seeing their congregations double in size. They set up soup kitchens and offer support to families hit by workplace raids and deportations.
"It is time for some compassion in the immigration debate," said Sister Christine Feagan, who ministers to Hispanics at St Mary's Catholic Church in Iowa. "Welcome the stranger."
But in a US election year with illegal immigration one of the most passionate issues, some candidates have a tough message for undocumented immigrants.
ANGER AT CATHOLIC CHURCH
Among the Republican candidates who take a tough line on immigration, one of the most outspoken is Mike Huckabee, a Baptist preacher who has drawn strong support from evangelicals.
Many religious conservatives in the United States take a sharply contrasting view of immigration from that of the Catholic Church.Some are angry that the Catholic Church helps people who break the law. Others accuse it of using support for immigration as a way to win back members as the church loses ground to evangelicals and secularism in Latin America.
"The Roman Catholic Church is aiding and abetting the criminal invasion of America from Mexico," wrote Ralph Ovadal, pastor of the Pilgrims Covenant Church in Wisconsin, in a booklet sold on the church's Web site.
Without the shelters in Mexico, most migrants would be forced to beg for food, sleep on streets, in the hot sun and freezing cold of the desert or on the muddy banks of the Rio Grande before attempting to cross.
"I'm extremely grateful for this shelter, but even without it, I would still try to get across," said 19-year-old Guatemalan coffee picker Raul Mintis, looking at a map of the United States in the Nuevo Laredo shelter.
The church denies any wrongdoing and says it is stepping in to fill the void created by the lack of a US immigration policy and the failure of Latin American countries to create more jobs for their people.
"While the governments of the United States and Latin America fail to provide workable policies, the church will do what it must to help the migrant," said Rafael Romo, Archbishop of Tijuana on Mexico's border with California. "We can't let these people be treated like animals."
