Populism's original sin: Short-term populist penalties and uncertainty traps

This paper investigates the immediate economic impacts of populist policies. In 2018, the Mexican president-elect held an unofficial referendum with less than 1% turnout to halt the construction of Mexico City's New International Airport. I show the policy is plausibly a natural experiment with nationwide impacts, preceding other macroeconomic shocks and populist policies dismantling economic and institutional checks. Using the synthetic control method, I find a 3.3% to 4.5% GDP reduction one year post-cancellation. Consistent with the uncertainty trap framework, this decline is due to heightened economic uncertainty and a significant drop in investment, reinforcing each other and leading to a prolonged economic downturn. The results highlight how populist policies can impose immediate economic costs by creating uncertainty traps, even before implementing institutional changes.