Do large firm dynamics drive the business cycle? We answer this question by developing a quantitative theory of aggregate fluctuations caused by firm-level disturbances alone. We show that a standard heterogeneous firm dynamics setup already contains in it a theory of the business cycle, without...

This essay suggests that the convergence controversy may reflect, in part, differences in perception regarding the viable set of competing testable hypotheses generated by existing growth theories. It argues that in contrast to the prevailing wisdom, the traditional neo-classical growth paradigm...

Large cities produce more output per capita than small cities. This may occur because more talented individuals sort into large cities, because large cities select more productive entrepreneurs and firms, or because of agglomeration economies. We develop a model of systems of cities that...

This paper proposes a simple theory of a system of cities that decomposes the determinants of the city size distribution into three main components: efficiency, amenities, and frictions. Higher efficiency and better amenities lead to larger cities, but also to greater frictions through...

We analyze the role of optimal income taxation across different local labor markets. Should labor in large cities be taxed differently than in small cities? We find that a planner who needs to raise revenue and is constrained by free mobility of labor across cities does not choose equal taxes...

Individual earnings are higher in bigger cities. We consider three reasons: spatial sorting of initially more productive workers, static advantages associated with workers' current location, and learning by working in big cities. Using rich administrative data for Spain, we find that workers in...

This Paper examines city formation in a country whose urban population is growing steadily over time, with new cities required to accommodate this growth. In contrast to most of the literature there is immobility of housing and urban infrastructure, and investment in these assets is taken on the...

Why do cities grow in population, surface area, and income per person? Which cities grow faster and why? To these questions, the urban growth literature has offered a variety of answers. Within an integrated framework, this chapter reviews key theories with implications for urban growth. It then...

We estimate the effects of major roads and public transit on the growth of major cities in the US between 1980 and 2000. We find that a 10% increase in a city’s stock of roads causes about a 2% increase in its population and employment and a small decrease in its share of poor households over...