Transit Investment and Neighborhood Transitions: Evidence from the Routes Not Taken

Transit projects reshape the built environment and impact access to employment. Disentangling transit construction impacts from pre-existing trends presents methodological challenges. We address reverse causality by identifying counterfactual station locations from Environmental Impact Statements as control areas within a difference-in-differences framework. Analyzing extensions across 15 light rail lines reveals that transit investments catalyze neighborhood change. The older adult population 55+ within 15-minute walking distance from new stations declines. Workers in station catchments have shorter commute distances but trend toward lower-skilled sectors. The proportion of workers aged 30-45 and 55+ increases, while the share of individuals under 30 declines. We identify this increasing population as "established essential workers." Housing prices show a marginally significant 9.8\% increase when using construction start dates in defining treatment timing, but effects become insignificant when using opening dates. In general, light rail transit investment supports older workers in lower-skilled jobs while deterring older, retired adults and those in other trades.