Adam Isacson

Defense, security, borders, migration, and human rights in Latin America and the United States. May not reflect my employer’s consensus view.


Charts: Drug Seizures at the U.S.-Mexico Border

We now have 11 months of data from U.S. Customs and Border Protection (CBP) about how much illicit drugs the agency seized at the U.S.-Mexico border during the 2023 fiscal year so far (from October 2022 to August 2023). That’s enough to compare this year’s drug seizures with previous years’.

With one exception—fentanyl—the data show a drop or stagnation in the amount of drugs being detected crossing the border.

Drugs manufactured from plants are turning up less often. A few years ago, Americans addicted to prescription opioids were turning to heroin made in Mexico (from the poppy plant), and heroin seizures were way up. That is no longer true: fentanyl competes with heroin, and it’s cheaper and easier to make. Heroin seizures have fallen sharply.

Data table

As is the case with all drugs except marijuana, 90 percent of this year’s border heroin seizures have taken place at ports of entry (official border crossings), where CBP’s Office of Field Operations operates—not the areas in between the ports where Border Patrol operates. 60 percent of all border-wide heroin seizures happened at California ports of entry (CBP’s San Diego Field Office).

Cocaine seizures are flat, despite evidence of increased production in the Andes (from the coca plant). 81 percent has been seized at ports of entry this year. 47 percent of all border-wide heroin seizures happened at California ports of entry (CBP’s San Diego Field Office), and another 23 percent at south Texas ports of entry (Laredo Field Office).

Data table

Marijuana seizures have been declining for a while. With so many U.S. states now allowing some form of legal, regulated sale of cannabis, there’s far less reason to take the risk of importing it from Mexico.

Data table

Marijuana is the only drug that mostly gets seized between the ports of entry. Only 25 percent was seized at ports of entry in fiscal 2023. Most marijuana gets seized in Texas (in 2023 so far, Border Patrol’s Rio Grande Valley Sector 31 percent, Border Patrol’s Big Bend Sector 22 percent, CBP’s Laredo Field Office 19 percent, and Border Patrol’s Laredo Sector 12 percent).

I haven’t done the research to understand why, but seizures of a major synthetic (not plant-based) drug, methamphetamine, have also fallen. 88 percent of meth got seized at ports of entry this year. Of all border-wide 2023 seizures, 63 percent happened at California ports of entry (CBP’s San Diego Field Office).

Data table

The one drug that’s being seized in far greater amounts is fentanyl. CBP seized 106 percent more of the highly potent, highly compact synthetic opioid in the first 11 months of fiscal 2023 than it did in the same period of fiscal 2022. (That’s measured in the weight of pills or other form of seized doses, not the weight of pure fentanyl.)

Data table

89 percent of fentanyl seizures took place at ports of entry during the first 11 months of fiscal 2023. The ports in California (San Diego, blue) and Arizona (Tucson, green) have accounted for 87 percent of all 2023 fentanyl seizures border-wide.

Data table

Fentanyl seizures continue to increase at the U.S.-Mexico border

Heroin seizures at the U.S.-Mexico border plummeted 72% since 2018, but seizures of a more potent synthetic opioid, fentanyl, jumped by 641 percent during the same period. Like heroin, 90 percent of fentanyl is seized at official border crossings (ports of entry) or Border Patrol interior road checkpoints.

This set of charts shows why a border wall won’t stop drugs

This graphic, from a San Diego Union-Tribune article that appeared Saturday, includes data that we almost never get to see: real-time information on U.S. border authorities’ drug seizures. (Click on it, or here, to view it larger.)

The data covers just one sector of the U.S.-Mexico border, which Border Patrol divides into nine sectors. This is the San Diego sector, which covers the western half of California’s border with Mexico. 2015 and 2016 data shows this to be the number-one sector, by far, for seizures of heroin and methamphetamine, both of which generally get produced in Mexico’s Pacific coast region. San Diego is also number two for cocaine seizures.

Seizure data gives you at least a vague idea of how much drugs are being trafficked through a sector. In 2015, the DEA reported [PDF], 49% of all heroin and 57% of all methamphetamine that got seized anywhere at the border was seized in the San Diego sector.

San Diego is also one of the most walled-off sectors, with fence built over 46 of its 60 border miles. So it’s a good test case for what a lot of border wall-building might achieve.

The chart here is even more useful because it breaks the seizure information down between what is seized at official border crossings, or “ports of entry” (bottom row), and what is seized in between the ports of entry, where Border Patrol operates and where walls get built (top row).

Look closely at the vertical (y-axis) scale on these charts. The maximum number at the top of each is several times higher for ports of entry than it is for “Border Patrol.” This means that several times more drugs get found at the ports—in cargo containers, hidden in vehicles, carried by people—than in the “in-between” areas where one might build a border wall.

Simply dividing the top-line of the “ports of entry” graphs by the top-line of the “Border Patrol” graphs—a horribly imperfect measure—gives you this general ratio of seizures.

  • Marijuana: 5 times more seizures at ports than between ports (400,000 pounds ÷ 80,000 pounds).
  • Methamphetamine: 17 times more seizures at ports than between ports.
  • Cocaine: 8 times more seizures at ports than between ports.
  • Heroin: 2.5 times more seizures at ports than between ports (though it’s a rough 1:1 ratio in 2016 and 2017).

The unavoidable conclusion here: building more border wall will have minimal effect on the transit of illegal drugs from Mexico into the United States. If you want to make it harder to transship drugs northward, you have to focus on the ports of entry, which have $5 billion in unmet infrastructure needs and are short-staffed by about 2,000 officers.

The ports are less “sexy” than a big concrete wall, but making them function better would do far more to disrupt drug flows. But the Trump administration’s funding requests have so far included no increases for ports of entry.

Postscript: Note that these charts’ 2017 column represents only the first six months of the government’s Fiscal Year 2017 (which started on October 1 of last year), which is why it looks like seizures went down during the most recent year. Double the size of that column, and you get a rough idea of what end-of-year 2017 seizures might look like. At the current pace, San Diego would see sharply more 2017 seizures of cocaine and methamphetamine, a small increase in heroin, and a sharp drop in cannabis.

This work is licensed under a Creative Commons Attribution 4.0 International License.