Many people wrongly believe that immigration is critical to the illicit supply of fentanyl in the United States. However, proponents of this view have offered little more than speculation to support it. New data obtained by the Cato Institute via a Freedom of Information Act (FOIA) request calls this belief into question. The new dataset shows that US citizens comprised 80 percent of individuals caught with fentanyl during border crossings at ports of entry from 2019 to 2024.

The FOIA dataset contains individual records regarding each person encountered by officials at US ports of entry from whom fentanyl was seized. Figure 1 shows the citizenship of individuals arrested with fentanyl from fiscal year (FY) 2019 to 2024, as of June. Overall, the dataset reveals that out of 7,569 individuals associated with a fentanyl seizure, 6,123 were US citizens, or 80.9 percent (see Figure 1 update)

The data are most relevant to understanding fentanyl seizure activity because the vast majority of fentanyl is seized at ports of entry, not between the ports where people cross illegally. Figure 2 breaks down fentanyl seizures by location. From FY 2015 to 2024, 88 percent of all fentanyl was seized at ports of entry, basically the same as in FY 2024. Another 4 percent was seized at vehicle checkpoints on highways after the ports. Only 8 percent was seized by Border Patrol on patrol, and many of those seizures came from vehicle stops as well. The seizure data supports the qualitative assessments of the Drug Enforcement Agency, Customs and Border Protection (CBP), and the Office of National Drug Policy based on investigative work. Even Bill Barr, while serving as attorney general under President Donald Trump, agreed.

Drug trafficking organizations hire US citizens because they are guaranteed the right of entry into the United States and are subject to less scrutiny at ports than individuals without citizenship. Data from the US Sentencing Commission reinforces the impression that US citizens are the primary method for fentanyl cross-border drug trafficking. From 2018 to 2023, US citizens accounted for 2,315 of the 2,905 convicted drug traffickers in southwest border districts (80 percent). The number of US citizens involved in fentanyl trafficking has risen more rapidly than it has for other traffickers since 2018.

These statistics naturally do not include the drugs that evaded detection or the traffickers who were not caught. However, just as surveyors do not need to interview every person in the country to learn that the country is politically divided, we do not need to see all people crossing the border to make conclusions about broad trends. Border Patrol apprehensions of immigrants crossing illegally constitute a significant sample size to make a reasonable inference about the unseen market.

From October 2018 to June 2024, Border Patrol made 8.5 million arrests and recorded 1,341 fentanyl “seizure events.” It is likely that half of these were of US citizens being stopped in vehicles at Border Patrol checkpoints or during highway patrols. Border Patrol also finds and records abandoned fentanyl as “seizure events.” It appears that fentanyl seizures occur during less than 1 in 12,000 Border Patrol encounters with border-crossing immigrants. Fentanyl smuggling is quite rare among the border-crossing population, and the flows that evade detection are much smaller than the number who are arrested.

It is logical to hire smugglers to bring drugs through legal crossing points because the probability of detection is so much higher when crossing illegally. CBP estimates that it seized only 2.98 percent of cocaine—the only drug it analyzed—that went through US ports of entry. This compares to its interdiction effectiveness rate for immigrants crossing illegally of over 75 percent (Figure 4). Even if CBP is far less effective at stopping crossers than it believes, there remains an incentive to attempt smuggling at ports of entry.

Eliminating Immigration Won’t End Fentanyl Smuggling

Many people believe that simply eliminating immigration is an easy answer to the overdose crisis in the United States, but these numbers cast cold water on this strategy. In fact, the overdose crisis worsened significantly during the years when legal and illegal immigration were greatly restricted (Figure 5). In 2020, when immigration of all types was radically restricted by President Trump, fentanyl overdose deaths increased by 56 percent. They spiked another 22 percent in FY 2021 when President Biden maintained Trump’s restrictions on legal entry and attempted to enforce his Title 42 asylum ban.

The travel ban at ports of entry was critical to facilitating the increase in fentanyl supply, leading to more deaths. US consumers preferred heroin until 2020, but with travel greatly restricted, cartels needed to get more product across with fewer trips. Fentanyl enabled this. Because it is 50 times more potent than heroin, it can supply the same market with 50 fewer crossings. The result was that fentanyl went from comprising a third of combined fentanyl and heroin seizures to over 90 percent when the travel ban ended, where it has remained (Figure 6).

Fentanyl is relatively easy to conceal in pockets, luggage, and vehicles because it is so potent. The prospect of easy cash has motivated an increasing number of Americans to participate in this illegal trade, tragically leading to the deaths of thousands of their fellow countrymen.

Detection Technology Is Not the Answer

Many people propose installing more effective screening tools at ports of entry to detect and interdict fentanyl. Unfortunately, greater detection technologies are not the answer to America’s drug problem. We have several lines of evidence supporting this conclusion.

First, marijuana was smuggled successfully into the United States for decades, despite being orders of magnitude easier to detect than any other drug. Marijuana is bulky, pungent, and extremely difficult to conceal. For this reason, it largely could not enter through lawful channels. It is also far less valuable per pound, so there is less financial upside to smuggling. Nonetheless, as I detail in my policy analysis on this subject, nothing abated the smuggling of marijuana––not doubling the Border Patrol, not building 600 miles of fencing, not the collapse of illegal immigration during the Great Recession. It was not until state-level legalization that the supply of Mexican marijuana disappeared. Changes in consumer demand ended trafficking, not enforcement.

Second, an unprecedented increase in seizures would not affect the availability of fentanyl unless drug cartels chose not to increase supply in response. We already know that they will. After the Border Patrol more than doubled in size, marijuana seizures rose alongside that increase, but marijuana availability remained the same, and its potency increased. Since the value of drugs on the Mexican side of the border is at most a tenth of the value of drugs on the US side, the interdiction rate would have to increase from its current 3 percent to nearly 90 percent just to double the price. But thanks to higher manufacturing output in Mexico, the fentanyl price has fallen so quickly that this historic effort would not necessarily even show up in a higher street price.

Third, there is almost no limit to how potent synthetic opioids can become. Even if CBP obtains a much higher rate of detection for fentanyl, drug manufacturers could swiftly shift to nitazenes, which are already showing up in the United States and are 20 times more potent than fentanyl. Nitazenes could supply the same fentanyl market with 5 percent of the current number of smuggling trips (or 5 percent as much weight). Of course, provoking such a shift in potency would result in even more tragedies. But shifts like this have already happened repeatedly in the drug market, including the shift from heroin to fentanyl.

Fourth, in the unlikely event that Mexican smuggling routes were sealed off, smugglers would adopt other methods. They would send it over in mailed packages, as they did before the rise of Mexican smuggling. Supposing all smuggling ended, Americans would just manufacture it domestically. Where there is demand, there will be supply.

Conclusion

Policymakers should focus on reducing demand for fentanyl rather than futilely trying to reduce supply. Cato scholars who predicted the fentanyl crisis have proposed many concrete ideas short of ending drug prohibition itself: Legalize fentanyl test strips to empower drug consumers to screen out fentanyl. Eliminate controls on methadone treatment. Allow doctors to treat addiction without risking jail time or losing their medical license. Reschedule diamorphine to allow for its use in treatment.

People have become so distracted by the immigration issue as an easy solution to the fentanyl problem that they are ignoring real solutions. People are dying because politicians have decided that empowering cartels to flood the market with fentanyl is better than deregulating addiction treatment, which would subsequently dry up demand for illicit drugs. Other countries have adopted better drug policies and have achieved better outcomes. None of those outcomes came from restricting immigration.