ABSTRACT

Rapid growth of the urban population has been a general trend throughout the world during the twentieth century. In 1950, 29% of the world’s population lived in urban areas. In 2000, this percentage was 47% (UNESCO, 2006). Today there are 21 megacities with more than 10 million inhabitants and more than 400 cities with population over 1 million. (City Mayors, 2008). This urban population expansion in the last 50 years has not occurred evenly around the world. Of these 21 mega-cities, 16 are located in developing countries. Of the 100 fastest growing cities, only three are in United States and the rest are in developing countries (City Mayors, 2008). The urban population of the 21st century will be composed, to a large extent, of poor people. Developing countries have now 2.6 times as many urban dwellers as high-income countries (UNFPA, 2007). Mega-cities act as engines of economic and social growth, and conversely, are accompanied by urban poverty and environmental degradation (El Araby, 2002).