For years, they smuggled drugs through tunnels. But as law enforcement learned about these underground channels, they turned to other means: trucks and other vehicles, stuffed with drugs in inconspicuous and creative ways, passing through legal ports of entry into the United States.

These details emerged from testimonies of former associates of the notorious Mexican drug kingpin Joaquín “El Chapo” Guzmán, who is on trial in New York over accusations that he led a multibillion-dollar enterprise that funneled drugs into the United States for more than two decades. These testimonies, reported by CNN and other media outlets, coincide with a budget impasse in Washington, where President Trump continues to push for funding for one of his signature campaign promises: a wall along the border with Mexico that he says will help keep illegal drugs and criminals from infiltrating the United States.

But the court testimonies are further evidence that a physical barrier, whether it’s fencing, steel slats or a concrete wall, would probably not stop drug trafficking. According to the Drug Enforcement Administration’s 2018 report, the majority of the heroin sold in the United States is channeled through legal entrances, and only a small percentage is moved “between ports of entry.”

“The best evidence suggests that the vast majority of hard drugs that enter the United States are smuggled in vehicles passing ports of entry. Clearly, if we want to make a smart investment that would slow down … drug trafficking, they would need to be at the ports of entry, not building a wall,” said Christopher Wilson, deputy director of the Mexico Institute at the Woodrow Wilson International Center for Scholars.

Jesús Zambada Garcia, a former leader of the Sinaloa drug cartel, testified this week that for years smugglers used trucks and other vehicles with hidden compartments to ply their trade. Witnesses also testified about the use of fishing boats.

A drug dealer who is testifying for the U.S. alleges Joaquin "El Chapo" Guzman once paid a $100 million bribe to former Mexican President Enrique Peña Nieto. (Reuters)

The testimonies seem to be corroborated by the federal government’s own findings. The DEA report says private vehicles and tractor-trailers passing through ports of entry are among the primary methods of smuggling drugs across the southwest border, with traffickers mixing contraband with legal goods.

Authorities have long said that tunnels are used to smuggle drugs. More than 200 tunnels have been discovered in the Border Patrol’s history. The longest was a half-mile tunnel, equipped with ventilation, rails and electricity, found in 2016 leading into San Diego from Tijuana.

“If you can tunnel underneath something, obviously a wall wouldn’t stop that,” Wilson said, adding that tunnels are usually built in areas where walls and fences, sometimes double or triple fencing, already exist.

Still, the president has continued to push for a wall, tweeting Tuesday that it’s the “only” way to keep the country safe. The stalemate between Trump, who refuses to budge from his demand for about $5.7 billion to start a physical barrier along the southern border, and Democrats, who are firmly against more money for the wall, has resulted in the longest federal government shutdown in U.S. history.

Guzmán’s trial began in November. He was extradited to the United States and charged in early 2017. Federal prosecutors allege that he led the Sinaloa cartel for 25 years, earning more than $14 billion in cash from selling drugs throughout the United States and Canada. They say he orchestrated the killing and torture of anyone who posed a threat to his drug empire. During opening arguments, prosecutors portrayed him as a ruthless man who used all sorts of mechanisms to traffic his drugs, earning himself the nickname “El Rapido” for the efficiency with which he was able to move cocaine and marijuana.

His attorneys argued that he’s a mere scapegoat whose “mythological” status is essentially a creation of the Mexican, U.S. and other governments looking to distract from corruption in their own ranks.

Guzmán has twice escaped from maximum-security prisons in Mexico. In 2015, he broke out of his native country’s most secure prison via a mile-long tunnel. He was recaptured in 2016, and Mexican authorities decided to send him to the United States to face trial.

Matt Zapotosky, Joshua Partlow and Ruby Mellen contributed to this article.

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