SONOYTA, Mexico — Reiner Ríos Gómez, who is from Honduras' capital, Tegucigalpa, lifted his shirt last week to expose a scar about 12 inches long in the middle of his back, where he said a machete hit him as he fled the robbers who were trying to steal his pay: 2,800 lempiras, or about $119, for half a month's work in construction.

To escape that life, he set out for the United States on Jan. 15, making it as far as Sonoyta, Mexico, a city on the Arizona border where roadside stalls sell the camouflage clothes and backpacks that migrants use to cross to the other side. Then he called a cousin in Houston.

"Why are you coming?" he said his cousin asked him. "They're going to send you back."

So Ríos, 33, settled down at a shelter in Sonoyta, unsure of what to do next. "I have nothing to go back to," he said. "And I don't know if there's anything for me on the other side."

Customs and Border Protection reported this week that the number of people caught trying to enter the United States illegally from Mexico had fallen in February to the lowest level in five years. The Trump administration said the sharp decline was a sign that its promises to hire more enforcement agents, deport more people and wall off the border were discouraging people from even trying to cross.

In interviews with migrants, their advocates, and workers at shelters and soup kitchens in Mexico, the United States and Central America, few quibbled with the idea that President Donald Trump had altered the climate for immigration.

It was clear that the ground had shifted on both sides of the border, and that the well-traveled route north to a better life had suddenly grown quieter, riskier and more desperate.

Since January, occupancy at one shelter in Nuevo Laredo, across the border from Laredo, Texas, has fallen by about two-thirds, according to its director, Aarón Méndez Ruiz. Other shelters in the United States and Mexico reported significant drops as well.

Six Central Americans staying at Méndez's shelter voluntarily surrendered to the Mexican authorities so they could be sent back home, he said, and about 40 more chose to return on their own.

"That had never happened," Méndez said. "People don't return."

In the Arizona desert, where blue flags flying 30 feet in the air mark where volunteers have left drums full of water, "there have been more water stations with no water use than usual," said Stephen Saltonstall of the aid group Humane Borders.

Last week, Ruben Garcia, the director of the Annunciation House, a shelter in El Paso, Texas, noticed that far fewer Central Americans were arriving than he was used to seeing. He asked those who did show up why that was.

"One hundred percent verbalized some version of, 'Your president,' " Garcia said.

The drop in border crossings is encouraging news, the homeland security secretary, John F. Kelly, said in a statement, "because it means many fewer people are putting themselves and their families at risk of exploitation, assault and injury by human traffickers and the physical dangers of the treacherous journey north."

At the same time, though, the dire economic and safety conditions that drive people from their homes have not changed.

At Casa del Migrante — a shelter in Caborca, 80 miles from the Arizona border — Mainor José Portillo, a soft-spoken 17-year-old from Choloma, Honduras, was waiting last week for his arm to heal. He injured it last month while trying to enter the United States.

Because he had no money to pay his smugglers, he had agreed to carry a backpack filled with 50 pounds of marijuana. But he was spotted by the Border Patrol as soon as he crossed, he said, so he dropped the backpack and was able to outrun the agents and make it back to the Mexican side.

Now he was trying to decide whether to try again. One thing was certain: He did not want to go back to Honduras.

"The gangs killed my cousin, and they said I was going to be next," he said.

Attempting an illegal crossing into the United States has become even more of a financial gamble than before. Officials and immigrant advocates in several countries said the criminal groups that control smuggling had been empowered as they began marketing themselves to migrants as the only way to evade the increased enforcement.

Smuggling fees from El Salvador, Honduras and Guatemala, the poverty- and violence-stricken Northern Triangle of Central America, have climbed as high as $15,000, advocates and officials reported, far above the average yearly income in the region.

Some migrants who might once have headed to the United States for safety and work are instead looking elsewhere, including Mexico, Belize, Costa Rica, Panama and even South America.

"If the United States isn't a country that will provide the guarantees, they will go somewhere else," said Vinicio Sandoval, executive director of the Independent Monitoring Group of El Salvador, a labor and legal rights organization involved in migration issues.

But a number of migrants along the route were holding to the unrealistic hope that Trump would change his mind about them.

Gustavo Adolfo Gómez, a 34-year-old cabdriver, said he had left Choluteca, Honduras, on Jan. 15 after gang members sprayed the taxi stand where he worked with bullets, killing two of his colleagues. He arrived on Feb. 27 at the Pueblos Sin Fronteras shelter in Sonoyta.

He said he planned to wait there a bit. For what? He was not sure.

"Maybe Trump will close his eyes one night and God will touch his heart," he said.

Sixty-nine men and one woman slept at Casa del Migrante in Caborca one night last week, on rolled rugs and skinny mats under a frayed plastic roof that did not completely keep out the rain. Just a month earlier, the shelter was twice as full.

Leonel Valderramas, 36, who stayed there last week, said he had departed in early January from San Pedro Sula, Honduras, the most dangerous city in one of the most dangerous countries in the world.

He heard updates about Trump's policies along the way, from fellow migrants who had boarded the same freight trains: "the wall, the raids, the deportation, everything," he said.

He hoped to make it to Houston, where he has friends. But then his wife called, telling him, "Si quieres, regresa" — come back if you want to.

He had come too far to turn back, he said. "But," he added, "what if I keep going and I get caught?"