Robustness Appendix for Urban Structure and Growth

In the simple version of the model presented in “Urban Structure and Growth”, we made assumptions designed to ensure that cities would perfectly specialize in terms of the industries producing in them. This assumption was for the purposes of simplicity, but also served to capture the idea that there are substantial di¤erences in the industry composition across cities. Nevertheless, cities are not perfectly specialized, and in this subsection we demonstrate two methods via which the above analysis could be extended to allow for multi-industry cities.