The border-effect literature confirms that sub-national units tend to trade more with the rest of their country than with foreign markets. However, it is likely that ongoing processes of trade integration will generate a trade-off between internal and external integration for sub-national units...

After the seminal paper by McCallum, various authors have estimated the effect of regional and national borders on trade. This paper digs deeper into the matter, estimating how the internal and external border effect is affected by the non-linear relation between trade and distance at different...