Smuggling foreigners into the United States earns transnational criminal organizations billions of dollars. Every year, hundreds of thousands of migrants shell out anywhere from $3,500 to $50,000 to get themselves into America illegally.

“The smuggling organizations, they’re in it for the money," said Paul Beeson, director of the Department of Homeland Security’s Joint Task Force's West division. "They’re not in it because they’re some altruistic folks who think they’re doing a service. The people, they’re a product. They’re chattel.”

But the crime organizations are not just moving people to make a few thousand dollars each time. They're moving human cargo because they've discovered how to leverage that operation in a way that helps ensure the success of their real money-maker, drug smuggling.

Drug trafficking became harder after President Trump took office, but traffickers have been surging migrants to the border for about a year to flood certain regions.

[Related: Fentanyl seizures at US-Mexico border up 750 percent]

“The way they use families and children to tie up Border Patrol resources while they bring narcotics through an adjacent point of the border ... creates operational challenges and that’s exactly why we’re trying to prevent the vulnerable populations from crossing between ports of entry illegally because it takes time and energy and focus away from the hardened smugglers and criminals,” U.S. Customs and Border Protection Commissioner Kevin McAleenan said during a recent trip to the Rio Grande Valley in South Texas.

Because federal law says all illegal immigrants must be apprehended and processed by Border Patrol, the surge this spring has forced agents and other resources to be diverted to regions where illegal crossings are most common, and this allows drug cartels to move their narcotics through spots that are left unguarded.

CBP is struggling to deal with this two-sided problem. To make matters worse, it is also losing more personnel this year than it is gaining. Officials told reporters during a recent tour of the border that transnational criminal organizations know how to exploit America’s weaknesses and have thrown a wrench into President Trump’s campaign promise to thwart illegal immigration.

Fleeting Trump effect on immigration

During Trump’s first few months in office, illegal immigration dropped to 45-year lows. The number of arrests, which is how the government counts the numbers of people trying to enter the country illegally, went from 60,000 or more in the final months of the Obama administration 16,000 in April last year.

But by summer of 2017, the relative trickle became a river, and apprehensions hit 35,000 in January this year. In March, the walls caved in and more than 50,000 people were reported being apprehended at the southwest border. That number remained above 50,000 again in April and May.

"Following the president’s inauguration, everyone knows the numbers dropped dramatically; 45-year lows in border crossings, including all demographics: kids, families,” the commissioner said. "And when the smugglers ... realized that this legal framework, the structure with which our agents and our partners in the interagency operate within hadn’t changed, that they could still be successful as a family crossing the border and being released for a multi-year process or as an unaccompanied child from further away than Mexico, that there’s a double standard under the TVPRA, the numbers started to creep back up."

Another year, another migrant surge

A week after Trump effectively ended the “zero-tolerance” policy, McAleenan met reporters inside the country’s largest migrant processing facility in McAllen, Texas.

As the government official responsible for all border personnel, he explained that the smugglers know how to game the immigration system. They pay close attention to every change in America's laws.

“This is an irregular migration. It’s a multi-year phenomenon, a change of patterns that’s dramatic, from single adult males primarily from Mexico, which were the primary border-crossers, well over 90 percent up to the end of this decade up to a change where more than half the people coming across the border are from further away, where a phenomenon that was really not significant one at all at all is a huge percentage of what we’re seeing and where families are coming across in record numbers in '14 and '16,” he said.

The 2014 surge was made up primarily of unaccompanied Central American children who were trafficked to the border and dumped there. Tens of thousands of minors were housed by the DHS when Jeh Johnson was head of the agency. The department's ability to house illegal immigrants changed two years later around the time of the presidential election.

"What changed in '16 was — in addition to the dynamics around the election — the fact that a district court judge in the Central District of California made an updated ruling interpreting the Flores settlement from the Ninth [Circuit] and that included the decision that accompanied children like unaccompanied children could not remain in DHS custody for more than 20 days,” McAleenan explained.

Because immigration hearings and processing were required for children who arrived at the border alone and were from countries south of Mexico, the border patrol couldn't determine whether each child in custody needed protection and could stay in the U.S. or could be sent back across the border immediately.

"So the ... deterrent was taken away and these families had to be released. And they’re on non-detained dockets with the immigration courts that can extend three to five years and beyond,” McAleenan said.

This spring, in the third migration surge in four years, drug cartels had showed once again that they find ways to game the system. The administration had ordered more federal law enforcement agents to be hired and for immigration laws to be enforced, but illegal immigration was soaring.

Staff draining away

Law enforcement struggled to catch up. Not only was CBP and its sub-agency, Border Patrol, dealing with the migration surge, but the agencies were understaffed. Responding to the crisis became harder.

A year and a half ago, Trump ordered 5,000 additional Border Patrol and 10,000 more ICE personnel to be hired. Congress has yet to fund the president’s mandate.

Agencies also have a serious retention problem that is further complicated by their extensive hiring process which includes a polygraph test that two out of three applicants fail. There is also a four-month training program that also slows things down.

Acting DHS Deputy Sec. Claire Grady testified to a Senate committee in February that Border Patrol was suffering a net loss of 400 staff a year. And of course, new hires are not as experienced as the people who are leaving the agency.

As of late September 2017, Border Patrol had 19,437 agents, 2,000 fewer than Congress had funded, and CBP had 23,079 employees, including nearly 100 air and marine officers, according to a CBP report.

The personnel shortage is nowhere more evident than on the border.

Rio Grande Valley is the epicenter

In late June, McAleenan visited the Rio Grande Valley Sector for the third time in a little over a month. It's one of nine Border Patrol sectors on the southwest border but it has accounted for 45 percent of the nation's illegal immigration in the past five years.

Illegal crossings are constant. One recent tour for reporters was interrupted twice so agents could be informed of suspicious activity less than a mile away.

The tour started five miles south of Mission, Texas, just east of the Anzalduas International Bridge in Granjeno, and headed toward a dirt track known as Rancon Road. A radio call came in: six people, including a baby, had just been seen apparently entering the U.S. across the river.

This is a high-traffic spot for arrests because it is here that traffickers, who have brought migrants from El Salvador, Guatemala, and Honduras, dump their charges and leave them to the mercies of the river and the Border Patrol.

The six had crossed the river on a raft after scouts alerted the traffickers that agents were not watching.

The media caravan drove to a crossroads where other agents had already made contact with a group of Hondurans. One woman said she was the mother of a 12-year-old girl standing next to her and another woman said she was the mother of a one-year-old boy she held in her arm. The women were clearly shaken but cooperated and did not complain as border agents took control.

They were loaded into a transport van, which took them to the Centralized Processing Center in nearby McAllen. There they would be processed, with the women probably kept with their children, following McAleenan's order that adults in families that arrived together should not be referred for prosecution.

The arrests took minutes from start to finish. It was something agents had done hundreds of times before.

How human smuggling works

Human smuggling unfolds in three ways. Some smugglers give people either real, stolen documents, or counterfeit papers to try to use at proper ports of entry. Other smugglers hide their people in car trunks or tractor trailers attempting entry into the U.S. But the bulk of illegal entry is of the sort we'd just witnessed, between proper entrances, said Beeson, who oversees the department's Southern Border and Approaches Campaign Plan.

Smuggling people is a difficult but massive operation, and it is undertaken by crime groups and individuals from Asia, Africa, Mexico, and South America.

“They’ve got employees ... in various places ... along the way ... Those types of organizations ... range from mom and pop shops to the more international in scope,” said Beeson. “Typically when you see the high-end fees, there’s an ocean that needs to be crossed and there’s more hands that have to touch them."

Beeson said people who pay to be trafficked do not realize what they are getting themselves into.

“This is a very dangerous enterprise for people who are seeking to sneak into the country,” Beeson said. “There’s the abuse that occurs where you’re in the hands of the smuggler, whether they’re beating you up for money or assaulting the women. Then there’s the threats from the environment that they choose to smuggle you through. People drown in that river [the Rio Grande] and die in that desert. The choice is the smuggler's. They make the decisions.”

Border Patrol stretched thin

Border Patrol in the Rio Grande Valley Sector is responsible for 315 river miles of frontier and their task is made more difficult by the lack of paved roads. During our three-hour tour, the only roads were unpaved and sometimes in miserable condition.

The lead driver hesitated to drive a few hundred feet down one road to where the six Hondurans had been caught because recent flooding might have made it impassable. But eventually he took us as far he could by car and we walked the final stretch in the 100-degree Texas heat.

"There’s some areas where we can’t even get to the border, much less move laterally along the border. We need accessibility. We need the ability to move, but they need to be all-weather roads,” said Melissa Lucio, patrol agent in charge of the McAllen Station.

But Lucio says she needs to have enough staff to patrol the border effectively even if there were decent roads to work on. "That’s going to be critical to our success, because let’s say I do get the cameras that I need and I detect an entry, if I don’t have the ability to affect the proper response, then what good is it?” she said.

McAllen Station employs 650 agents, but Lucio says she needs 300 more to deal with the tide of illegal migrants.

Agents must also respond to medical emergencies, and there have been plenty since recent flooding along the Rio Grande, which is known south of the border as the Rio Bravo del Norte. Undercurrents are “furious” and rescues are frequent.

“There hasn’t been a week ... without us finding a drowned victim or even trying to rescue someone ... unsuccessfully ... before they have drowned,” said Lucio. “You would think that the smugglers would slow down with all of the rain that fell over the last few days, but that didn’t slow them down. They still kept coming. They kept bringing over people and leaving them on the banks to fend for themselves.”

Limited wall construction underway

In addition to hiring more staff, the border security effort is looking forward to building more wall and improving infrastructure. CBP announced plans in the spring to use $1.6 billion in new congressional funding to build 47 miles of replacement wall for what is already in place, and another 53 miles of new wall to fill in gaps. CBP wants an additional 1,000 miles of new fence and says the $25 billion Trump requested in January could get it done.

Border infrastructure may be deficient but it is also, in places, impressive. The entry point at Hidalgo, one of the Rio Grande Sector’s three ports, features 20-foot steel gates a few hundred feet apart from each other guarding dirt roads down to the river. They were installed in 2009 to prevent migrants who had just crossed the river from coming up the riverbank and getting deeper into the U.S.

A further 35 new gates are slated to be added to make smuggling more difficult.

The drugs change, but the war remains the same

The flow of smuggled opioids and methamphetamines rose in the first eight months of this fiscal year, and have already surpassed the levels of 2017.

In fiscal 2017, U.S. Border Patrol and CBP's Office of Field Operations officers confiscated 1,132 pounds of fentanyl, a synthetic opioid 50-100 times stronger than morphine. This year’s seizures are already 15 percent higher than last year's total.

More than 53,000 pounds of meth have also been seized already, which is 97 percent of the 2017 total of 54,393 pounds.

Cocaine seizures are down at the border, but they’re up in Puerto Rico, where traffickers try to smuggle drugs from South America to Florida. CBP officers based in the Puerto Rico seized 65,890 pounds of narcotics from drug cartels in 2017, more than any year on record.

Jeffrey Quinones, public affairs officer for CBP’s Puerto Rico and U.S. Virgin Islands outposts, said the eastern Caribbean has served as a trafficking pit stop for decades, but the recent increase shows that cartels are using the 100-mile-wide island to circumnavigate the southwest border.