Tokyo is the undisputed champion of mega-cities. With a population of 37.8 million, it dwarfs second-place Delhi. The Japanese capital has such a big lead in population that even though it’s expected to lose about half a million people over the next 16 years, it will still be the world’s biggest metropolis in 2030, according to a new report by the United Nations:
Here is a list of the Top 10 "mega-cities" by population in 2014 and projected in 2030.
Some of the mega-cities on the 2014 list aren't projected to rank as high in 2030 ... For example, New York, Osaka, and Sao Paulo will no longer make the top 10, and Mexico City will barely hang on as the sole representative outside of Asia and Africa.
This projection reflects the major shift driven by the urbanization in Asia and Africa, particularly in India (404 million projected new city dwellers by 2030), China (292 million), and Nigeria (212 million).
Why is the balance shifting so radically? Mostly because the rest of the world is already highly urbanized, while Africa and Asia are home to nearly 90% of the world’s remaining rural population.