In 1950, there were just two cities in the world—New York and Tokyo—that were considered “megacities,” that is, urban areas with populations of at least 10 million. By 2018, there were thirty-four such cities and the United Nations estimates that by 2035 there will by forty-eight megacities. America has just two megacities, New York-Newark (18.8 million) and Los Angeles-Long Beach-Santa Ana (12.4 million).
Tokyo (37.39 million), Delhi (30.29 million); Shanghai (27.05 million), São Paolo (22.04 million), and Mexico City (21.78 million) top the list of megacities.
Source: “Around 2.5 Billion More People Will Be Living in Cities by 2050, Projects New UN Report,” United Nations Department of Economics and Social Affairs, n.d., https://www.un.org/en/desa/around-25-billion-more-people-will-be-living-cities-2050-projects-new-un-report