Source: United Nations. http://www.un.org/esa/population/unpop.htm

The 15 Largest Cities of the World, 1975- 2015 (in millions)

A high proportion of the world’s population lives in large urban agglomerations. There were 83 cities or city systems with populations of more than 1 million in 1950, 34 of them in developing countries. In 2000, there are over 280 such cities and this number is expected to double by 2015. All the new millionaire cities and 12 of the world’s 15 largest cities are in developing countries. If cities of 8 million are considered, 28 existed in 2000, with 22 of them in developing countries. In 1950, only the largest city in the world (New York) had more than 10 million people and by 2015 12 cities will have a population of more than 15 million inhabitants. Tokyo, the largest, had 35.2 million inhabitants in 2005, but Mumbai (Bombay) is expected to have a similar population by 2015.