Governments and energy operators are frequently confronted with opposition to the construction of new energy infrastructure and a lack of public support. This is also true for the planning of new high-voltage overhead transmission lines. In this context, a question of interest for policy makers and energy operators is how residents react when they realize that they may be affected by future transmission lines in close proximity to their homes. This study provides evidence of how local residents respond to the announcement of transmission line corridor route alternatives (TLCRAs). By means of a natural experiment, it estimates the causal effects of spatial proximity to proposed TLCRAs during the planning phase of an energy project. The results reveal that proximity significantly enhanced residents' risk perceptions with respect to landscape deterioration, property/house value reduction, and damages to human health. We also found that increasing proximity decreased residents' support for grid expansion and increased the likelihood of performing information seeking behavior and becoming a member of a local citizens' initiative. Finally, our findings suggest that the relationship between spatial proximity and the dependent variables are appropriately modeled by a distance decay function, showing that effects attenuate with increasing distance from the infrastructure site.