How Does Fentanyl Reach the United States?

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In March 2025, President Donald Trump followed through with his promise to impose sweeping tariffs on three of the United States’ major trading partners: Canada, China, and Mexico. He cited the “extraordinary threat” posed by fentanyl, a lethal and highly potent synthetic opioid and the countries’ failure to prevent the flow of illegal fentanyl into the United States. 

The opioid crisis has been ravaging the United States for the past several years, although fatalities sharply declined in 2024. At the crisis’s peak in 2022 and 2023, drug overdoses caused more than 111,000 fatalities per year, most of them driven by fentanyl. Fentanyl and synthetic opioids quickly rose to become the leading cause of death for Americans aged eighteen to forty-five. 

China and Mexico, two countries that see elements of fentanyl traffic to the United States, have stepped up measures to contain the flow of the drug. Canada has done the same, despite it being responsible for almost none of the fentanyl that winds up inside U.S. borders.

What is the status of the fentanyl crisis?

Annual fentanyl-related deaths remain in the scores of thousands but are trending downward for the first time in years. Fatal overdoses have dropped nationwide by more than 21 percent since June 2023, data from the U.S. Centers for Disease Control and Prevention (CDC) shows. The death toll dipped below eighty-five thousand deaths in a twelve-month period ending in September 2024; while that’s still significantly high, it’s a level not seen since 2020. 

Experts say the decline is in large part due to concerted efforts to curb trafficking by the Joe Biden administration in cooperation with other countries, namely China and Mexico.

Yet in announcing tariffs, the Trump administration has pointed to the countries’ roles in trafficking fentanyl into the United States as a reason to impose tariffs, and has claimed that fentanyl deaths range anywhere from three hundred thousand per year to “tens of millions” of mortalities—figures that law enforcement and public health experts say are inaccurate.

How much U.S. illicit fentanyl supply comes from Canada, China, and Mexico?

Mexico

Mexico is a major recipient of precursor chemicals used as ingredients for fentanyl via illicit networks set up by cartels. The cartels, after manufacturing the drug, then often hire U.S. citizens to smuggle it across the border. Due to fentanyl’s potency, it is much easier to smuggle undetected as only a small amount is necessary to transport. Mexico has been the main source of fentanyl into the United States: nearly all of the 21,900 pounds that U.S. law enforcement seized last year was at the southern border while only 43 pounds of fentanyl was seized at the Canadian border, according to U.S. data. 

The country has been facing mounting pressure to clamp down; President Claudia Sheinbaum has upped government enforcement toward gangs, and Mexico made the biggest arrest of fentanyl traffickers in its history in December. U.S. Drug Enforcement Administration (DEA) data also indicates that the amount of fentanyl seized at the southern border last year dropped by around 20 percent. 

China

China’s role is a little more complicated. Beijing banned fentanyl and all potential fentanyl variants within its own borders in 2019 and maintains that it does not allow the drug to be made. Chinese companies are widely known to make precursor chemicals, many of which have legitimate reasons to produce controlled substances, principally in the medical sector. However, these precursors are often purchased by transnational criminal organizations in Mexico to synthesize fentanyl. 

For years, China has remained resistant to tackling the supply chain of precursor chemicals, pointing to its own ban on the drug as its lack of contribution to the fentanyl issue. But Beijing reached agreement in 2024 with the Biden administration to impose tough new measures on precursor chemicals. The two sides also agreed to boost cooperation to stem drug trafficking, which U.S. officials say has helped damper fentanyl’s flow into the United States.

Canada

Canada plays virtually no role in the U.S. fentanyl influx, especially compared to the other countries. The country contributes less than 1 percent to its southern neighbor’s street fentanyl supply, as both the Canadian government and data from the DEA report. 

Notably, Americans are heavily involved in the fentanyl crisis as well; U.S. citizens have accounted for around 90 percent [PDF] of fentanyl trafficking convictions in recent years.  

How have these countries responded? 

The leaders of Canada and Mexico negotiated a pause on implementing tariffs and have since ramped up their antidrug measures. Canada unveiled a $1.3 billion plan to secure the border and appointed a fentanyl czar. Mexico announced that it would immediately reinforce its border with another ten thousand National Guard troops aimed specifically at stopping fentanyl in its tracks.

After Trump’s announcement, the Chinese foreign ministry said in a statement that the tariffs will actually undermine the cooperation against drug trafficking. Other U.S. experts warn of the same thing. Trump’s move to pause all foreign assistance has already halted anti-fentanyl work in Mexico, officials familiar with the matter told Reuters. Tariffs are slated to go into effect on March 4—a closely watched move to see how it will affect fentanyl flows, as well as costs of living and geopolitical relations.

All three countries have vowed swift tariffs on the United States should Trump’s tariffs take effect as scheduled. Both Canada and Mexico have pledged similar tariffs in response to the U.S.-imposed 25 percent levies. China noted that it would take “necessary countermeasures” to defend its interests and announced duties ranging from 10–15 percent to counter the United States’ 10 percent tariffs. Trump responded with yet another 10 percent tariff, totaling a 20 percent levy on all Chinese imports.

Will Merrow contributed to the graphics for this article.