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

Cities with more than 10 million Inhabitants, 2007 (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 10 million are considered, 19 existed in 2007 with Tokyo, the largest, having 35.2 million inhabitants. In the span of half a century several cities have more than tripled their population.