Urban Scaling and the Dynamics of Cities

Cities connect people with various skills and interests in a multi-component, interconnected system, which displays properties consistent with other complex systems observed in nature, such as scaling. Urban scaling is the empirical observation that as cities increase in size, they achieve agglomeration economies in socioeconomic indicators (i.e., superlinear scaling in GDP, income, crime) and economies of scale in terms of physical infrastructure (i.e., sublinear scaling in road length, length of electricity cables). This thesis focuses on the foremost (if not only) model in the literature for explaining scaling of internal indicators in cities, the Origins of Scaling in Cities model by Bettencourt. The model derives a number of superlinear, sublinear, and linear scaling exponents for different indicators from basic first principles in economic geography and physics. It combines classic ideas in economic geography of cities, particularly spatial equilibria, with the properties of social and infrastructural networks. In doing so, the model introduces new variables for describing internal processes in cities. The thesis consists of three papers, each with foundations in the Origins of Scaling in Cities model but adding new contributions to the field. The first paper, Dynamics of Urban Scaling, brings in a temporal component to the model by looking at how scaling parameters changes in cities over time, particularly in response to growth or decline, as well as urban planning policies. The second paper, A New Metric for City Sustainability Based on Urban Scaling Theory, takes a closer look at the costs and benefits of cities that are outlined in the model, and it examines the point at which cities can be considered to be maximizing net benefit. The third paper, The Physics of Urban Growth Revealed by City Scaling, looks at scaling in the context of the city as a thermodynamic system, presenting a new approach to understanding energy use in cities and the transformations that occur as urban populations and economies grow. The thesis is book-ended by discussion surrounding the ability of cities of different sizes to meet the needs of their residents, and the inevitable tradeoffs that exist in rapidly growing cities.Ph.D