Externalities play a central role in most theories of economic growth. We argue that international externalities, in particular, are essential for explaining a number of empirical regularities about growth and development. Foremost among these is that many countries appear to share a common long...

We analyse how spatial disparities in innovation activities, coupled with migration costs, affect economic geography, growth and regional inequality. We provide conditions for existence and uniqueness of a spatial equilibrium, and for the endogenous emergence of industry clusters. Spatial...