Rapid Urbanization in Developing-Country Cities

“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