“In 2008, for the first time in history, more than half of the world’s population will be living in towns and cities. By 2030 this number will swell to almost 5 billion, with urban growth concentrated in Africa and Asia. While mega-cities have captured much public attention, most of the new growth will occur in smaller towns and cities, which have fewer resources to respond to the magnitude of the change. … Migration is a significant contributor to urbanization, as people move in search of social and economic opportunity.”
State of World Population 2007:
Unleashing the Potential of Urban Growth
New York: United Nations Population Fund