The Mayan Train, one of Mexico's most ambitious infrastructure projects, has sparked intense debate over its socio-environmental impacts. It offers a unique lens to study the intersection of economic development and environmental politics. While such projects promise economic benefits, they can also impose significant environmental costs, influencing political preferences in complex ways.

This study examines how the Mayan Train’s economic and environmental effects shaped voting behavior along its route. Using spatial and intensity-based difference-in-differences approaches, I analyze electoral outcomes in areas affected by the train. In regions with pre-existing rights of way, where minimal deforestation accompanied economic benefits and infrastructure improvements, voters rewarded the incumbent party, consistent with economic voting theory. Conversely, in areas marked by extensive deforestation and environmental degradation, voters punished the incumbent and significantly increased their support for the Green Party.

These findings reveal the dual influence of economic development and environmental harm on voter behavior, showing how infrastructure projects can simultaneously generate economic gratitude and environmental backlash. This study provides robust evidence of how environmentally harmful projects reshape electoral dynamics, offering critical insights for scholars, policymakers, and advocates navigating the tensions between development, sustainability, and democratic accountability.