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 c”

Keywords: Megacities; the world’s largest cities; urban internal and external driving forces; global urban development; human urban settlement;