Source: United Nations, Department of Economic and Social Affairs, Population Division (2006). World Urbanization Prospects: The 2005 Revision. New York: United Nations.

World Urban Population, 1950-2005 with Projections to 2020 (in billions)

Between 1950 and 2005 the global urban population has more than tripled to reach 3.15 billion. While urbanization has considerably slowed down in developed countries, the developing world is where cities are growing the most. It accounted for 68% of the urban population in 2000 and by 2020, 77% of the global urban population is expected to be in developed countries. This process will be accompanied with significant surges in urban mobility demands. On the other hand, mobility demands in urban areas can be more efficiently satisfied with collective transportation than mobility demands in rural areas.