“…Besides the methodological similarity to the macro-econometric literature, our research directly connects to a wide range of urban economics research that aims at establishing the unidirectional causal impact of transport supply on economic outcome measures using either quasi-experimental (Ahlfeldt, 2013;McDonald & Osuji, 1995;McMillen & McDonald, 2004;Michaels, 2008) or instrumental variable (IV) designs (Baum-Snow, 2007;Baum-Snow, et al, 2012;Duranton & Turner, 2011Holl & Viladecans-Marsal, 2011;Hornung, 2012;Hsu & Zhang, 2011). These studies typically implicitly or explicitly assume that the supply of infrastructure is uncorrelated with the previous trend in observed economic outcome in a particular case or that an IV is at hand that predicts transport supply, but is conditionally uncorrelated with the outcome.…”