Source: United Nations, Department of Economic and Social Affairs, Population Division (2018). World Urbanization Prospects: The 2018 Revision, Online Edition.
A large share of the world’s population lives in large urban agglomerations. There were 83 metropolitan areas with populations of more than 1 million in 1950, a figure that increased to 160 by 1975, and a surge to 514 in 2015. Of the agglomerations of more than 12 million inhabitants in 2015, the largest was Tokyo, with a population of 37.3 million. In the span of half a century several cities have more than tripled their population, underlining that urbanization has been the world’s leading socioeconomic change.