A key element missing from the structural gravity literature is a legitimate validation of theory. By design the reduced-form gravity equation is adept at predicting bilateral trade flows. To make inferences beyond trade flows, however, theoretic models should be consistent with other observable...

Borders affect the composition, not only the level, of interregional trade. In disaggregated U.S. Commodity Flow data, border effects vary substantially across commodities. Substantial border-induced compositional change suggests the possibility that standard estimates suffer from aggregation...

What are the barriers that separate nations; While recent work provides intriguing clues, we have remarkably little concrete evidence as to the nature, size, and shape of barriers. This paper offers direct and indirect evidence on trade barriers, moving us toward a comprehensive geography of...