Cities of workers, children or seniors? Stylized facts and possible implications for growth in a global sample of cities

A large literature documents how cities vary in their skill structure and how this has implications for their economic growth. By contrast, how cities vary in their age structure and the potential implications of this for their economic growth has been a hitherto largely neglected research area. Using novel data from a variety of historical and contemporary sources, we first show that there is marked variation in the age structure of the world's largest cities, both across cities and over time. We then study how age structure affects economic growth for a global cross-section of mega-cities and find that mega-cities with higher dependency ratios - i.e. with more children and/or seniors per working-age adult - grow slower. Overall, and despite the many data and econometric challenges posed by this type of analysis, we advocate for more research on the subject given its importance.