Mexico-U.S. Migration: What to Know

Unlawful crossings at the U.S.-Mexico border dropped sharply last year. Now, Mexico and countries in Central America are bracing for mass deportations from the U.S. after the Trump administration takes over.

Crossings into the United States from Mexico have dropped sharply since last year. But countries south of the U.S. border are waiting nervously to see if President-elect Donald J. Trump orders mass deportations.

The possibility that millions of undocumented immigrants could be expelled — what would be the largest deportation program in American history — has sent shock waves through Latin America and sowed confusion among migrants and asylum seekers.

“We see dark times coming for the migrant community,” said Irineo Mujica, the Mexico director of People Without Borders, a transnational advocacy group. “Anyone who falls prey to the Trump administration is now going to be devoured, chewed up and spat out.”

Migrants being processed at the U.S.-Mexico border after being detained by the Border Patrol in New Mexico in November.Paul Ratje for The New York Times

Mr. Trump has said that Mexico is allowing an “invasion” of migrants into the United States. But the current situation on the ground tells a different story.