Land titling and political alternation: seeds of Mexico’s drug war

The Mexican drug war has escalated dramatically since 2007, yet its roots lie in municipal turf wars of the 1990s and early 2000s involving the main drug-trafficking organizations operating in the country. We trace these turf wars to two concurrent shocks: the weakening of the PRI's long-standing dominance in local offices, and PROCEDE, the programme that converted PRI-dominated communal ejidos into individually titled parcels. By transforming untitled land into marketable property, PROCEDE made rural parcels far easier to acquire or extort. At the same time, opposition victories at municipal and state levels dismantled PRI-brokered protection networks, leaving incumbent cartels exposed. Together, marketable land and vanishing political cover created fertile ground for rival organizations to invade and clash. Using a difference-in-differences framework, we show that municipalities exposed to both shocks—the PROCEDE rollout and opposition victories—experienced a rise in organized-crime deaths during 1995–2006. The surge is strongest when an opposition mayor is elected in the same year that the governorship also turns against the PRI, signalling the collapse of protective networks. Cartel-presence data also reveal that these municipalities attract both first-time entrants and multiple rivals, confirming that violence stems from competition over newly contestable territories.