International economic integration yields large potential welfare effects, even in a static constant returns competitive world economy. Our method is novel. The effect of border barriers on trade flows is often inferred from gravity models. But their rather atheoretic structure precludes welfare...

Why does illegal trade often flourish without formal enforcement, but sometimes fail? Why do illegal trade-reducing policies often fail? Why do States often appear to tolerate illegal trade? A model of trade with cops and robbers provides answers. `Safety in numbers' is a key element: the...

We develop a structural gravity model that introduces scale effects in bilateral trade. Scale effects and incomplete passthrough give two channels through which exchange rates have real effects on trade patterns. Estimates from Canadian provincial trade data identify these effects through their...