Does traffic congestion negatively impact the economic growth of metropolitan areas? This article reviews the findings of three research directions addressing this question. First, research on first-order impacts indicates that the economic value of congestion-induced travel delay is tenuous since travelers adapt. Second, research on second-order impacts suggests that congestion slows metropolitan growth, inhibits agglomeration economies, and shapes economic geographies. Third, research on public-sector congestion mitigation policies identifies significant fiscal burdens despite limited success at reducing congestion. In sum, research on individual, business, and public-sector responses to congestion demonstrate a shift from congestion mitigation toward adaptation.