Growth of Cities over the Past 5000 Years

Discussion

Chris Chase-Dunn et al. :

Growth of Cities over the Past 5000 Years: "George Modelski's (2003) recent study of the growth of cities over the past 5000 years points to a phenomenon also noticed and theorized by Roland Fletcher (1995) – cities grow and decline in size, but occasionally a single new city will attain a size that is much larger than any earlier city, and then other cities catch up with that new scale, but do not much exceed it. It is as if cities reach a size ceiling that it is not possible to exceed until new conditions are met that allow for that ceiling to be breached. This notion of size ceiling will also be useful for studying changes in the sizes of polities." ... "The first city size upsweep corresponds with the Uruk expansion in early Bronze Age Mesopotamia. Then there is another upsweep in the Iron Age, a fall-back and then the rise of Islamic Baghdad. The huge size of Baghdad in the tenth century did not really constitute a new ceiling in the evolution of city sizes because it was an outlier that was not replicated for 1000 years. Thus we should call this a surge rather than an upsweep. So there have been four upward sweeps that led to new plateaus of city growth in the Central System: the original heartland of cities in Mesopotamia and Egypt, the rise of Alexandria and Rome in the Iron Age, then a decline followed by the Baghdad surge, and then the well-known rapid upsweep of modernity in East Asia, Europe, and North America. After the 1950s a new ceiling of around 20 millions is reach by the largest urban agglomerations. Megacities in Brazil, Mexico and China caught up with the largest core cities in this period, causing the global size distribution of cities to flatten in the second half of the 20th century "

(https://www.sociostudies.org/almanac/articles/cycles_of_rise_and_fall_upsweeps_and_collapses_changes)