In recent empirical literature on spatial agglomeration, many papers find evidence consistent with location-specific externalities of some sort. Our willingness to accept evidence of agglomeration economies depends on how well key estimation problems have been addressed. Three issues are...

In this paper, I examine the relationship between increasing returns to scale and the geographic concentration of economic activity. Using data on U.S. counties, I estimate the structural parameters of the Krugman (1991) model of economic geography. The specification I use, which is derived from...

We test for home-market effects using a difference-in-difference gravity specification. The home-market effect is the tendency for large countries to be net exporters of goods with high transport costs and strong scale economies. It is predicted by models of trade based on increasing returns to...