Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Using a geo-coded micro-level panel dataset for Spanish manufacturing firms, I estimate the effect of access to highways on firm-level productivity. To identify the causal effect of highways, I have relied on different fixed-effects specifications, instrumental variables and controls for geography, geology and history. Since highways also attract economic activity, leading to local density increases, which in turn could affect productivity through agglomeration benefits, I also present estimations that control for local employment densities. The results show that highways raise firm-level productivity directly and beyond the effect of density. Additional results show that highway benefits are unevenly distributed across sectors and space.