Megacities, the World Largest Cities Unleashed: Major Trends and Dynamics in Contemporary Global Urban Development

Abstract

By the year 2010, 10% of the world’s urban population was concentrated in one of 23 “megacities,” those with at least10 million people. In this study we ask two basic questions: will the megacity trend continue into the immediate and long-term future? and why do more and more people continue to concentrate in what are already the world’s biggest cities? In our empirical analysis we investigate the “internal” and “external” driving forces behind the global phenomenon of urban concentration over the past 6 decades. During this period the world’s biggest cities have continued growing faster than all the others, and we expect this trend to continue into the foreseeable future. We also emphasize a real difference between what we call “mega-local cities,” which are mainly located in the world’s developing countries, and the much more economically powerful “mega-global cities” of the developed world. Our findings also suggest that urban growth tends toward polarization: at first the largest city in a specific country outpaces all other cities, but over time we detect a more balanced urban system emerging for the country as a whole. We also observe the spatial rules underlying these trends, noting that the size of megacities is strongly correlated with country size. To identify the “external” factors that are associated with megacity growth, we investigate the effect of more than 20 variables, aggregated into 5 major clusters: trade and commerce; government power; transportation networks; technology and innovations; and financial and business services. Our analysis points to a clear correlation between the strength of these factors and the size of the largest city in a given country. We identify three sets of factors that appear to be of major importance in accounting for urban concentration: the development of transportation networks; the spread of technology and innovation; and the growth of financial and business networks, all of which appear to be at work transforming “mega-local cities” into “mega-global cities.