ABSTRACT
We present a primer of the basic framework and solution techniques for models of the spatial economy with mobility of trade and workers ows. We document a number of facts about the ow of people and goods both within and across countries. We then show how these empirical patterns are consistent with a simple version of one of the most successful theories in modern economics: the gravity model. In this framework we highlight the importance of mobility and trade frictions by considering the impact of the Interstate Highway System under different scenarios. Our approach is designed for teaching this material at an advanced level but is still accessible to audiences without expertise on the topic.
