Does most illegal fentanyl sold in the US come through Mexico?

Question

The Atlantic claims:

most illicit fentanyl used in America, where 32,000 people died from fentanyl last year, comes through Mexico. Mexican cartels lack trained chemists to make fentanyl from scratch, so they buy precursors in bulk from China. After that, making finished fentanyl is simple.

What's the level of evidence for this (China->Mexico) being the most common route for illegal fentanyl sold the in the US?

Although the source does investigate how the Chinese sell the precursors, it doesn't provide more backing for the paragraph I quoted.

Answer 1

I suspect that might be based on estimates using as proxy the US seizures of fentanyl at borders (points of entry more precisely). If we use that method, the claim is only nominally correct, i.e. in terms of quantity of cut product. If product purity is taken into account however, shipping by package/air (supposedly directly from China, but this bit is unclear as to the certainty) seems to take the first spot. From a RAND report/testimony.

Seizure data at ports of entry offer some insights into the dimensions of illicit imports. CBP reports seizing synthetic opioids, including fentanyl, at land points of entry and checkpoints on the southwest border, as well as at mail and express consignment facilities and other air ports of entry. Table 1 shows that in FY 2018, seizures of fentanyl near or at the border ports of entry significantly outweighed those at mail and express consignment carrier facilities. However, after adjusting for purity, almost 70 percent of fentanyl seized by CBP in FY 2018 arrived by air, mostly at mail and express consignment carrier facilities. Analysis of FY 2017 seizure data reports a similar breakdown. Law enforcement and congressional investigations have suggested that many of the packages at mail and express consignment facilities originate from China. If CBP seizures represent the true nature of trafficking patterns, then these preliminary calculations support law enforcement’s conclusion that China is an important source country of illicitly manufactured synthetic opioids.

Frankly I find it pretty weird that they cannot be certain where packages get mailed from, at country-level granularity...

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It seems however that there may have been a trend change in 2019; a news piece from July says:

The number of drug seizures involving high-purity fentanyl sent via mail from China "dropped precipitously" this year, according to Thomas Overacker, the executive director of the Office of Field Operations at U.S. Customs and Border Patrol.

Only several pounds of fentanyl have been intercepted this year at U.S. mail facilities and airports, predominantly originating from China. "Most of the illicit fentanyl" entering the country "does so at ports of entry along our southwest border," Overacker told members of a congressional subcommittee Tuesday.

It's possible that the Atlantic piece (which is from August) may have relied on this newer info/testimony for their claim. I guess we'll have to wait and see year's end DEA's summary/report for a more definite, numerical conclusion.

The same news piece from July offers some possible reasons behind this trend change, again citing some officials:

The shift from China to Mexico is very recent and largely the result of successful drug control strategies implemented in the past two years.

Specifically, officials cited Beijing's decision in May to criminalize all fentanyl-related substances following U.S. pressure. The move led to a decline in the number of Chinese vendors willing to export fentanyl products, according to David Prince with Homeland Security Investigations' transnational organized crime office. [...]

As a result of requiring data on the sender, recipient and the contents of an international parcel, as well as new technology to scan packages, the postal service saw a 1,000% increase in the number of parcels seized containing synthetic opioids between 2016 and 2018. Domestically, the agency saw the number of opioid parcel seizures increase by 750% in the same timeframe.

In 2019, USPS statistics suggest that international seizures are down and domestic seizures are trending up. "This shift may suggest synthetic opioids are increasingly entering the country through means other than international mail," Chief Postal Inspector Gary Barksdale told lawmakers.

If one can offer a better answer, I'll accept that of course.

Answer 2

These articles (especially the second) are writen from a religious-based viewpoint, but the magazine's news facts tend to be researched and accurate.

According to a Senate report released in January, Americans purchased nearly $800 million worth of fentanyl pills directly from Chinese chemical labs over a two-year period. Taking advantage of the anonymity provided by digital currencies like Bitcoin, Chinese sellers mailed an estimated 500 packages of fentanyl through the U.S. Postal Service.

Chinese labs have partnered with Mexican cartels to smuggle fentanyl into America. Mexico’s national security commissioner told the newspaper Reforma that most fentanyl entering Mexico from China comes through the port of Manzanillo in the state of Colima. Once the fentanyl is unloaded, it is smuggled into the U.S. by either the long-established Sinaloa cartel or the up-and-coming Cartel Jalisco Nueva Generación.

China is also the main supplier of the precursor chemicals like ephedrine and pseudoephedrine that Mexican cartels use to manufacture methamphetamines, a stimulant to the central nervous system that 1.2 million Americans are addicted to.

— from Fentanyl: China's Secret Weapon to Destabilize America | theTrumpet.com

And:

“Recent Chinese doctrine articulates the use of a wide spectrum of warfare against its adversaries, including the United States,” said a 2014 report from U.S. Army Special Operations Command. “The People’s Liberation Army (pla) colonels Liang and Xiangsui outline China’s vision on how China will attack the United States through a combination of military and nonmilitary actions. … These methods include trade warfare, financial warfare, ecological warfare, psychological warfare, smuggling warfare, media warfare, drug warfare, network warfare, technological warfare, fabrication warfare, resources warfare, economic aid warfare, cultural warfare and international law warfare” (Sept. 26, 2014).

— from China’s Drug War—Against America | theTrumpet.com