Universality in Urban Growth

In the era of rapid urbanization, understanding the mechanism of urban growth is critical to a better future of humanity. Models for urban growth can prepare policy makers to address the economic and social changes in their growing cities. Over the last decades, the physics of cities has revealed the mechanisms of urban growth from the universal characteristics that are largely observed in the main pillars of cities: function, shape and size. This article introduces the theoretical frameworks - urban scaling, fractal geometry and Zipf’s law-for universality in the function, shape and size of cities. In addition, we review the recent findings for a unified model of urban growth, including recapitulation, hierarchy and migrations.