To address the economic significance of national border effects, this paper provides evidence on two fundamental questions: (1) Do large border effects arise because of high perceived-price wedges between foreign and domestic products, or because imports and domestic goods are very close substitutes?; and (2) If price wedges are important, do they reflect distortionary barriers to trade or do they arise from nondistortionary factors, such as differences in transactions costs or product characteristics? I conclude that, while border effects may imply barriers, welfare costs, and a role for policy, distortions are probably not as substantial as initial border results suggested.

Transport time increases with distance traveled, and time is valuable. We show the implications of these facts for global specialization and trade: products where timely delivery is important will be produced near the source of final demand, where wages will be higher as a result. In the model, timely delivery is important because it allows retailers to respond to final demand fluctuations without holding costly inventories, and timely delivery is possible only from nearby locations. Using a unique dataset that allows us to measure the retail demand for timely delivery, we show that the sources of U.S. apparel imports have shifted in the way predicted by the model, with products for which timeliness matters increasingly imported from nearby countries.