SAN SALVADOR — For many of the migrants who step off the bus at a national reception center for deportees, their belongings in backpacks and shoelaces in their pockets, this is not the end of the journey, just a way station.

President Trump’s “zero tolerance” policy? Family separations? A coming border wall?

“That doesn’t change anything at all,” said Ronaldo Eduardo Valencia, 39, on Friday as, fresh off the deportation bus, he collected himself in a clean, well-lit immigration facility here that was funded by the U.S. government.

Eduardo, a shoe salesman from San Salvador, has been deported at least four times over the past decade, including once after he was detained while wandering lost in the desert outside Tucson. On this trip, he never made it past southern Mexico, where he was detained by authorities and put on a bus back home. The days when he could pay for smugglers are long gone, but with an 11-year-old son — a U.S. citizen — in Los Angeles, he has no intention of staying here.

“I’m going to try again,” he said.

The forces that drive illegal immigration to the United States — violence, poverty, the search for better jobs and schools for children, the chance to reunite with relatives — are powerful and have sustained decades of migration by millions of people from Central America and Mexico.

And yet, these flows are not static, and they respond to various factors, including White House rhetoric and border policies, the cost of smugglers, seasonal patterns, job opportunities and the intensity of violence at home. The number of detentions of Salvadorans along the U.S.-Mexico border — a proxy for overall illegal crossings — has fallen sharply over the past year, while apprehensions of Guatemalans have risen.

Those who have been deported here say they realize the consequences of an illegal crossing could be higher under the Trump administration than they were before.

“You have to think about yourself and your children,” said Jorge Campos, 21, who arrived in San Salvador on Friday after three months in detention in Houston, following his third attempt to join his relatives in Virginia.

“If I go back again, the judge could give me up to one year. My fear is to be there and be imprisoned,” he said.

So far in the eight months of this fiscal year, 7,167 Salvadorans have been detained as part of a traveling family, down from 24,122 in the full 2017 fiscal year, according to U.S. Customs and Border Protection statistics. This year, the number of Guatemalans apprehended has spiked to 29,278 “family units,” already surpassing the previous full year’s total.

Salvadoran officials attribute the recent drop in migrants to a declining homicide rate in the Central American country and a government plan, backed by the United States, that focuses attention and economic development on 50 hot spots of gang activity in the country. Last year, El Salvador’s homicide rate was 60 killings per 100,000 people, the highest in Central America, but still far below that of the prior two years.

Officials here also acknowledge that Trump’s policies probably have discouraged some families from risking the trip.

Before the U.S. presidential election, the number of migrants crossing the border spiked, and many said at the time that they wanted to cross before Trump built his wall. After the election, the numbers plummeted because many Central Americans worried that the Trump administration would treat them more harshly.

After a months-long lull, detentions from across the region have been climbing again. The Trump administration responded with a “zero tolerance” policy aimed at prosecuting all who cross the border illegally — rather than just giving them an administrative punishment — a move that involved separating them from their children. Trump has since issued an executive order stopping the family separations.

“I think all migrants are calculating the risks, especially with the separation of children and parents,” said Hector Aquiles Magaña, secretary general of the migration commission in the Foreign Ministry. “It could be a deterrent, but it’s not the only one because we can’t reduce [a migrant’s calculation] to just one thing.”

Politics and natural disasters also play a role. Many of those traveling in the U.S.-bound migrant caravan across Mexico that outraged Trump earlier this year said that they left because of chaos after last year’s contested presidential election in Honduras. So far this year, Nicaragua has faced a government crackdown on a nationwide protest movement.

Juan Carlos Guardado, 32, from the southern state of Sonsonate, said that despite the increased risks of crossing the border illegally, he intended to try again. Guardado has already tried to go back four times since he was deported in 2016 after living in Miami for 11 years.

He has two children, ages 3 and 9, in Florida.

“The truth is I’m thinking of trying to go again because I don’t want to bring my daughters here to this country, where there is so much poverty,” he said at the reception center for deportees. “I think it’s better that they’re there.”

What would Trump have to do so that he wouldn’t migrate again? “I don’t know, I don’t know,” he said. “I honestly don’t know.”