More than two thirds of guns recovered at Mexican crime scenes originate in the U.S. For decades, Mexico has struggled with staggering levels of gun violence fueled in large part by weapons trafficked across its northern border.

Now an investigation published by The Conversation has arrived at a new estimate of the scale of this illicit gun trade between the U.S. and Mexico in 2022: 135,000 guns.

Investigative journalist Sean Campbell and Topher McDougal, a professor of economic development at the University of San Diego, spent a year combing through multiple databases and court documents and conducting interviews to understand how the flow of guns works.

Their investigation reveals where in the U.S. the guns are coming from, what impact these American guns are having in Mexico, and how difficult it is for American law enforcement agencies to prosecute those trafficking guns across the border.

Listen to Campbell and McDougal talk about their investigation on The Conversation Weekly podcast.

You can read the full investigation here.

This episode of The Conversation Weekly was written and produced by Mend Mariwany and Gemma Ware. Mixing and sound design by Eloise Stevens and theme music by Neeta Sarl.

Newsclips in this episode from PBS News, CGTN, France24, ABC 7 and NewsNation.

Listen to The Conversation Weekly via any of the apps listed above, download it directly via our RSS feed or find out how else to listen here. A transcript of this episode is available on Apple Podcasts.

Sean Campbell and Topher McDougal do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations.