Maricopa County, in Arizona, has emerged as the “main epicenter” of illegal arms trafficking into Mexico, according to John Lindsay-Poland, coordinator of Stop US Arms to Mexico, an initiative that studies the illicit flow of weapons between the two countries.
The region contains multiple ZIP codes associated with large numbers of firearms that are trafficked into Mexico and later recovered in crimes there, according to records obtained through public-information requests. The phenomenon is fueled by permissive gun laws and a high concentration of firearms dealers. Data provided and analyzed by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) show that a significant share of these weapons, particularly assault-style rifles and large-caliber firearms, cross the border shortly after being legally purchased in the United States and ultimately end up in the hands of organized crime groups in Mexico.
Maricopa County is located in the south-central part of Arizona. According to the 2020 census, it was home to just over four million people, representing roughly 62% of the state’s population. That makes it both Arizona’s most populous county and the fourth most populous in the United States. Its county seat, Phoenix, is the state capital and the country’s fifth-largest city.
Speaking in Mexico City during the Academic, Artistic and Cultural Conferences for the Reduction of Firearms, Lindsay-Poland argued that while firearms are purchased across thousands of locations in the United States, certain hotspots stand out. Maricopa County, home to densely populated cities such as Tempe, Mesa, Glendale and Phoenix, accounts for a high volume of weapons trafficked to Mexico and used in crimes on U.S. soil. The ATF measures this through what it calls “time to crime,” the period between a firearm’s legal purchase and its recovery at a crime scene.
“The problem lies in the permissiveness of the legal market,” Lindsay-Poland explains. “A person can walk into a gun shop and legally buy five AR-15 rifles, two .50-caliber rifles and 1,000 rounds of .50-caliber ammunition without ammunition registration or by purchasing at gun shows with no oversight.”
The activist says that, after analyzing firearms with a time-to-crime of less than one year between early 2024 and May 2026, researchers identified just over 4,000 weapons, the vast majority originating in Maricopa County, particularly in Phoenix.
One case highlighted by the U.S. Department of Homeland Security last August illustrates the scale of the problem. After a two-year investigation, authorities announced five indictments and the seizure of weapons and ammunition. The case involved 21 individuals, including Fernando Daniel Castro, a 24-year-old resident of Phoenix, and his alleged associates.
Prosecutors accuse Castro of recruiting and paying so-called “straw purchasers” to acquire firearms through legal channels with the intention of illegally transferring them to third parties. As part of the operation, authorities seized 100 firearms and more than 125,000 rounds of ammunition in Arizona. Officials also said arrests were made on both sides of the border, in the United States and Mexico.
According to Corridors of Violence, a report by Stop US Arms to Mexico, 14 of the 15 ZIP codes from which the largest numbers of firearms were purchased and later recovered in Mexico within a year between 2023 and 2024 were located in Arizona. More than two-thirds of the firearms recovered in Mexico in 2024 and traced back to the United States came from just three counties: Maricopa County, in the Phoenix metropolitan area (53.9%); Pima County, home to Tucson (8.8%); and Harris County, in the Houston area of Texas (6.4%).
Lindsay-Poland says his organization has several theories as to why Maricopa County has become such a prominent hub in the arms-trafficking trade. One factor, he argues, is that the area’s urban density allows purchasers to operate with less scrutiny than in rural communities. The local firearms market is also permissive, extensive and militarized. “For that reason, weapons flow to places with stricter laws, such as Mexico and California,” he adds.
Mexico has strict firearms laws and only two gun stores, both operated by the military. As a result, criminal organizations source their weapons abroad, above all in the United States. The NGO points to assault rifles such as the AR-15 and the AK-47, known in organized crime circles as cuernos de chivo (“goat horns”), as well as .50-caliber rifles. Because these weapons are banned in California, buyers turn to Arizona instead.
“In the past two years, the concentration of purchases of cuernos de chivo in Arizona trafficked to Mexico in short periods has grown rapidly,” Lindsay-Poland explains.
“In this area, the Century Arms brand, specialized in AK-47 rifles, stands out; it has become the most sought-after brand trafficked to Mexico,” he continues. “Although its production volume is small compared with manufacturers such as Smith & Wesson, Glock, Beretta or CZ, the proportion of its weapons that ends up trafficked is comparatively very high.”
A second explanation, according to Lindsay-Poland, in shifting trafficking routes. The internal conflict among criminal factions in Sinaloa has generated high demand for weapons in both Sonora and Sinaloa, making them the Mexican states with the highest number of firearms seizures.
Rival factions such as Los Chapitos and La Mayiza avoid moving weapons through hostile territory. Between 2015 and 2024, the Arizona-Sonora-Sinaloa corridor gradually displaced the route linking the Rio Grande Valley in Texas with Tamaulipas as the principal channel for the flow of illegal firearms.
Lindsay-Poland also points to what he describes as the reverse logistics of drug trafficking. “Traffickers use the same routes and transportation networks used to move drugs into Arizona and use them to bring weapons back. They use the same routes, the same networks.”
More recently, The New York Times reported on a group of teenagers and young men aged between 16 and 19, known as The Phoenix Boys, who operate within networks of straw purchasers used to acquire AR-15-style rifles and handguns, such as Glocks, from gun stores in Arizona or through intermediaries.
The group uses platforms such as WhatsApp, Telegram and Signal to coordinate orders, prices and deliveries with buyers linked to organized crime groups in Mexico. According to the report, members often stage fake thefts and tell police that their firearms were stolen, or store weapons in temporary safe houses before they are moved across the border into Mexico.
Lindsay-Poland says this “sad situation,” while involving only a relatively small number of people, highlights both the lack of legitimate opportunities for some young people and the ease of access to firearms in Arizona, where gun culture is deeply entrenched and often begins at an early age.
“It is essential to encourage community conversations about sales limits,” he says. “Given the difficulty of changing federal laws because of the influence of the gun lobby, individual merchants still have the discretion to refuse atypical sales to a single buyer. Regulating these practices is a priority, because criminal organizations sustain their operations and the trafficking of substances such as fentanyl through this illicit flow of weapons.”
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