In a moment filled with powerful political symbolism, Pope Francis prayed Wednesday at Mexico's dusty northern border for the thousands of migrants who have died trying to reach the United States and appealed for governments to open their hearts, if not their borders, to the "human tragedy that is forced migration."
"No more death! No more exploitation!" he implored.
It was the most poignant moment of Francis' five-day trip to Mexico: The first Latin American pope, who has demanded countries welcome people fleeing persecution, war and poverty, praying at the border between Mexico and El Paso, Texas, at a time of soaring anti-immigrant rhetoric in the U.S. presidential campaign.
Francis stopped short of calling for the U.S. to open its borders during a Mass celebrated just yards from the frontier. But in his homily, beamed live into the Sun Bowl stadium on the El Paso side, Francis called for "open hearts" and recognition that those fleeing gangland executions and extortion in their homelands are victims of the worst forms of exploitation.
"We cannot deny the humanitarian crisis," the pope said on the last day of a six-day visit to Mexico. "Each step, a journey laden with grave injustices: the enslaved, the imprisoned and extorted; so many of these brothers and sisters of ours are the consequence of trafficking in human beings."
"Injustice is radicalized in the young; they are 'cannon fodder', persecuted and threatened when they try to flee the spiral of violence and the hell of drugs. Then there are the many women unjustly robbed of their lives," he added.
A major manufacturing center, the gritty industrial city of Ciudad Juárez has been hammered by drug violence in recent years. It also an important crossing for Mexicans, Central Americans and Asians trying to reach the United States illegally.
Francis also praised the work of activists who "are on the front lines, often risking their own lives" to help those caught up in the migration crisis. "By their very lives, they are prophets of mercy," he said.
And then, in a pointed message, Francis greeted to the 30,000 people gathered in the Sun Bowl to watch the simulcast on giant TV screens, saying, "Thank you, brothers and sisters of El Paso, for making us feel like one family and the same Christian community."
Francis, the son of Italian immigrants to Argentina, had wanted to cross the border in solidarity with other migrants when he visited the U.S. last fall. That wasn't possible for logistical reasons, so he did the next best thing on Wednesday by coming within a stone's throw of the fence to pray and lay a bouquet of flowers next to a large crucifix that is to remain at the site as a monument to his visit.
Immigration reform remains one of the most divisive issues in U.S. politics, and a key theme in the 2016 presidential vote.
The pope's stance is starkly at odds with the anti-immigrant rhetoric of candidates for the 2016 Republican U.S. presidential nomination.
Donald Trump has surged ahead of his rivals with his message that Mexico is "killing" the United States with cheap labor, while sending over criminals and rapists. He has also promised to build a huge border wall.
Trump last week dubbed the pope "a very political person", saying he believed the Mexican government had put him up to the border visit.
"I don't think he understands the danger of the open border that we have with Mexico," Trump said in an interview last week with Fox television. "I think Mexico got him to do it because they want to keep the border just the way it is. They're making a fortune, and we're losing."
He and fellow GOP hopeful Sen. Ted Cruz have vowed to expel all the estimated 11 million immigrants in the U.S. illegally.
"To suggest that the pope is an instrument of the Mexican government, no. That is very strange indeed," said Father Federico Lombardi, the Vatican spokesman, shortly before the pontiff arrived in Ciudad Juarez.
"The pope always speaks of the problems of immigration. If Mr. Trump were to come to Europe he would see that the pope has said the same things about immigration to the Italians, the Germans, the French and the Hungarians."
Earlier on Wednesday, the pope issued a scathing critique of capitalism, echoing remarks made in the U.S. last year, saying that God will hold accountable "slave drivers" who exploit workers.
"The flow of capital cannot decide the flow of people," the Argentine pontiff said, denouncing "the exploitation of employees as if they were objects to be used and discarded".
"God will hold the slave drivers of our days accountable," he said.
The pope has in the past called money "the dung of the devil" and has decried what he calls the "evils" of unbridled capitalism, prompting criticism from U.S. business leaders.
Francis returned to Italy Wednesday night. His plane took off from the border city of Ciudad Juarez.