Here's one route where immigration has slowed since Biden's new U.S. border rules

NECOCLÍ, Colombia — The wharf in this town on Colombia's Caribbean coast used to be packed with migrants from all over the world boarding boats to take them across the bay to the start of the Darien Jungle.

A thick, roadless patch of rainforest on Colombia's border with Panama, the Darien Jungle has become a harrowing passageway for hundreds of thousands of people headed for the United States without a visa to enter.

But this flow of migrants has started to abate.

Last month, the Biden administration replaced pandemic-era border restrictions with new rules for entering the U.S. that are, in some ways, tougher on migrants. Now, those caught entering the U.S. without a visa could face criminal prosecution and a five-year ban from reentering the country. Those seeking asylum must first prove they were denied asylum in a country they traveled through on their way to the U.S.

U.N. officials tell NPR that before the new rules took hold on May 11, between 1,000 and 1,500 migrants were crossing the Darien Jungle every day. Now, they say, that number has dropped to between 500 and 700.

Natalie Vásquez, who manages one of the main ferry services in Necoclí, immediately felt the impact. She says her ticket sales to boat passengers heading to the Darien have dropped by half.

"The reduction started right on May 11," she says.

The changes are also visible on Necoclí's waterfront. It used to be packed with migrants, who couldn't afford hotels, camping out in tents as they prepared to cross the jungle. Now, most of the tents are gone and tourists have reclaimed the sandy beaches.

At a shop in the town center, Edis Quintero is trying to hawk secondhand winter jackets, sweaters and roller suitcases he purchased from migrants who needed cash and wanted to lighten their loads for the jungle. But on a recent afternoon, Quintero had no customers.

Another merchant, Javier Soto, who sells rubber boots, flashlights and portable stoves to jungle-bound migrants, says his sales had been booming but, in recent weeks, suddenly dropped off. He adds: "The town seems empty."

But this lull may be temporary because the factors driving migration are getting worse across much of South America, says César Zúñiga, who is in charge of emergency management for the Necoclí town government.

Venezuela remains mired in an economic crisis that has prompted more than 7 million people to flee the country since 2015. Ecuador is plagued by gang violence and drug-related crime while in Peru, the arrest of former President Pedro Castillo led to months of protests that paralyzed the economy.

As a result, Zúñiga says: "We are preparing for another surge in migrants."

Although their numbers are down, there remains a steady flow of migrants through Necoclí.

On the wharf on a recent morning, boat passengers strapped on life jackets, wrapped their luggage in plastic, gulped water and bought last-minute food supplies. Most are migrants from Venezuela but there's a smattering of Africans, Chinese, Ecuadorians and Haitians.

They're a nervous bunch because the most daunting part of their journey lies just ahead. They'll spend up to a week on foot hiking through the Darien Jungle to the first village on the Panamanian side of the border.

"We bought medicine and are preparing ourselves psychologically so there will be no surprises in the jungle," says Reiler Peña, 35, who sold used cars in the Venezuelan city of Valencia until the country's economic crisis forced him to leave. To get in shape, he says, "I was climbing the hills outside of Valencia. I trained every weekend."

But even the most robust travelers can run into trouble. Hundreds of people have been robbed or raped, and some have drowned in fast-flowing rivers, in the Darien Jungle. Officially, 36 migrants died there last year but the U.N. International Organization for Migration says anecdotal evidence points to many more fatalities whose remains were neither recovered nor reported.

However, migrants are so desperate to get to the U.S. that, last year, nearly a quarter of a million people braved the route. That was a record amount of migrant traffic through a region once deemed so dangerous and impenetrable that engineers who were building the Pan-American Highway, that runs from Alaska to Patagonia, gave up, leaving the 60-mile-wide "Darien Gap."

Among those buying ferry tickets in Necoclí was an Ecuadorian bus driver who says he left his homeland after he was threatened by gang members demanding extortion payments.

"They pulled a knife on me twice because I didn't want to pay them off," says the bus driver, who doesn't want to give his name for security reasons. "I was really scared. That's why I fled."

Farther down the beach, Rudy Heredia explains that she fled her native Venezuela five years ago and resettled in Peru. There, she sold empanadas while her husband worked construction. But protests and roadblocks following the arrest of former President Castillo cut off the flow of building supplies to much of the country and her husband lost his construction job.

"We were getting desperate so we decided to get out," she says.

For Heredia and other migrants here in Necoclí, their pathway to the north seems especially daunting. First, they must make it across the Darien Jungle in one piece. Then, they have to travel through a half-dozen countries to the Mexican-U.S. border. After all that, they'll need to navigate the onerous new U.S. immigration rules.

Still, none of this has stopped Lewis Flores, who is heading north with several fellow Venezuelans. He says: "Even if we get deported from the U.S. five times, we will come back five times."