McALLEN, Tex. — President Trump traveled to the Rio Grande Valley earlier this month and made his case for building a wall on the Southern border — needed, he said, to keep America safe from a variety of dangers that are continuing to make their way across the frontier from Mexico.
To help make his point, the evidence was laid out on tables: a big bag of cash, bundles of drugs, high-powered firearms, all confiscated by law enforcement agents working the borderlands in South Texas.
“This is just all recent. This is all very recent,” Mr. Trump said, pointing to the illicit exhibit in front of him. Mr. Trump was not shy about his disgust for the illegal goods: “It looks pretty brutal. This is not a manufactured deal, as you say. This is the real stuff.”
But the display at the president’s Jan. 10 round table, it turns out, had little to do with what happens along unfortified reaches of the border. An examination of the seized items suggests that a border wall would not have stopped most of the items from entering the United States, or, in the case of several weapons displayed in front of the president, from leaving the United States for Mexico.
Many of the items on display were seized on international bridges on the Texas border, detected by canines and Customs and Border Protection officers. Some of them were found during traffic stops or, in one case, inside a South Texas home, and it’s hard to know how they entered the country.
“It’s not complex,” the president said, after various officials described the items on the table. “If we don’t have a barrier, a very substantial barrier of some kind, you’re never going to be able to solve this problem.”
But of course, the story of illegal border trafficking is complex. And one of the biggest takeaways to be gleaned from Mr. Trump’s exhibit table was that nearly all of the items were intercepted by vigilant border agents — federal employees who have not been paid since the fight over a border wall led to a partial shutdown of the federal government on Dec. 21.
The AK-47 and the 9-millimeter pistols
The tableau in front of Mr. Trump included an AK-47 assault rifle and multiple 9-millimeter handguns. Though Mr. Trump seemed to take credit for the “all recent” seizures of illegal goods, these weapons were actually seized in June 2016, the month before Mr. Trump officially won the Republican nomination for president.
When a vehicle drove south from the Texas border town of Mission and onto the Anzalduas International Bridge bound for Mexico, C.B.P. officers searched the car and found the weapons, according to an agency spokesman. There were also 20 ammunition magazines found in the vehicle, the spokesman said.
American-made guns have illegally flowed south into Mexico in large numbers for years. A 2013 study by the University of San Diego found that nearly half of American firearms dealers are dependent on Mexican sales, with an estimated 253,000 firearms purchased annually between 2010 and 2012 to be taken across the border.
The bag of cash
Stacks of $20 bills bundled in a plastic bag totaling $362,062 sat on one table. Just days before the president arrived in McAllen, the cash had been inside the South Texas home of Edsgardo Coss-Vallejo.
Mr. Coss-Vallejo had been living in the United States on a visa, but overstayed his allowed time in the country. When Hidalgo County authorities and federal agents showed up at his house to investigate, Mr. Coss-Vallejo allowed them inside to conduct a search of his home. Border Patrol canines alerted on a duffel bag containing the cash. Mr. Coss-Vallejo denied ownership of the money.
Mr. Coss-Vallejo was arrested on suspicion of marriage fraud and currency smuggling, and he was deported to Mexico.
The methamphetamines and the heroin
After a large X-ray scanned a tractor-trailer entering Texas from Mexico at the Pharr-Reynosa International Bridge in September, Customs inspectors wanted a closer look. Canines did the rest and detected the drugs, according to a C.B.P. spokesman.
Authorities found 117 kilograms of methamphetamines and 12.5 kilograms of heroin concealed in the ceiling of the truck, the spokesman said. A majority of heroin that enters the United States from Mexico crosses not through remote stretches of unfenced desert, but through legal ports of entry, such as the border crossing in Pharr, Tex.
“But there’s no way to know how much gets through,” said Fulton T. Armstrong, who has worked as a national intelligence officer at the Central Intelligence Agency, on the National Security Council and on the Senate Foreign Relations Committee, focusing on Latin America.
“The biggest shipments come through legal, established ports of entry,” Mr. Armstrong said in an interview, though he added that there are also examples of drug smuggling that do not occur at official border crossings. Mr. Armstrong added: “Carrying this stuff requires sophistication. You don’t just put it in your pocket, you don’t carry large suitcases or bags when you come through non-ports of entry.”
This has raised questions about Mr. Trump’s argument that a wall would help curb drug flows.
“Would setting up a fence help? No. There’s no evidence at all,” Mr. Armstrong said.
The AR-15 rifle and the .50-caliber rifle
A .50-caliber sniper rifle took up a big part of one wooden table, with an AR-15 rifle positioned flat on its side alongside it.
In November 2017, Homeland Security Investigations agents, working on a tip from C.B.P., found the sniper rifle during a traffic stop in South Texas, according to a C.B.P. spokesman. The AR-15 was found the same way — by H.S.I. agents in South Texas, but in January 2018.
It is unclear where the weapons were headed, or whether they even originated in Mexico. Border Patrol agents infrequently encounter firearms smuggled across the Rio Grande, or into the United States between bridge crossings. Again, most seem to be heading the other way.
“The thing that’s missing from the debate is the southbound stuff,” Mr. Armstrong said. “The weapons, the cash.”