CIUDAD JUAREZ, Mexico — 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 and one of the most powerful images in recent times: History’s 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 US presidential campaign.

Francis stopped short of calling for the United States to open its borders during a Mass about a half-mile 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 the thousands of Central and South Americans who are fleeing gangland executions and extortion in their homelands are victims of the worst forms of exploitation.

‘‘We cannot deny the humanitarian crisis which in recent years has meant the migration of thousands of people, whether by train or highway or on foot, crossing hundreds of kilometers through mountains, deserts and inhospitable zones,’’ he said. ‘‘They are our brothers and sisters, who are being expelled by poverty and violence, drug trafficking and organized crime.’’

And then, in a pointed message, Francis added a politically charged greeting to the 30,000 people gathered in the Sun Bowl to watch the simulcast on giant TV screens.

‘‘Thanks to the help of technology, we can pray, sing and celebrate together this merciful love which the Lord gives us, and which no frontier can prevent us from sharing,’’ Francis said in Spanish. ‘‘Thank you, brothers and sisters of El Paso, for making us feel like one family and the same Christian community.’’

Francis, a son of Italian immigrants to Argentina, had wanted to cross the border in solidarity with other migrants when he visited the United States 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 and laying a bouquet of flowers next to a large crucifix that is to remain at the site as a monument to his visit. As the faithful looked on from both sides of the border, Francis blessed the cross and three smaller ones, which the Vatican said were to be sent to the diocese of Ciudad Juarez, Las Cruces and El Paso.

The border Mass marked the climactic end of Francis’ five-day swing through some of Mexico’s poorest and most marginal states, where drug-fueled violence has soared thanks to the complicity of police and other public institutions.

In a speech Wednesday to workers and employers, Francis warned that without job opportunities, Mexico’s youth risk being seduced into the drug trade. ‘‘Poverty becomes the best breeding ground for the young to fall into the cycle of drug-trafficking and violence,’’ he said.

He urged employers to think instead of the Mexico they want to leave for their children.

‘‘Do you want to leave them the memory of exploitation, of insufficient pay, of workplace harassment?’’ he asked. ‘‘What air will they breathe? An air tainted by corruption, violence, insecurity and suspicion or, on the contrary, an air capable of generating alternatives, renewal and change?’’