A two-wave death story: fentanyl overdoses in the US, bullets in Mexico

We establish a link between the fentanyl crisis in the US starting in 2013 and a second wave of drug-related violence in Mexico. We argue that the demand for fentanyl from the US pushed emerging Pacific-based Mexican drug trafficking organizations to reoptimize their trafficking routes, leading to new clashes and violence, often in locations barely affected by the first wave of violence caused by the 2007 Mexican War on Drugs. Exploiting the differential impact that the Mexican War on Drugs and the demand of fentanyl had on different municipalities, we estimate that fentanyl caused about 20 additional homicides per 100,000 inhabitants.