Special Feature by SALT

Note: All population figures are for the metropolitan area.

This millennium is perhaps the beginning of the age of megacities - huge metros that are already sprouting across the globe, but more rapidly in the developing world. The growth of megacities - those with populations exceeding 8 million – has been phenomenal. In 1900 there were none. In 1950, there were two – London and New York. In 1990 there were twenty-one. In 2025, the World Resource Institute predicts, there will be thirty-three – and all but six of the 33 will be in the developing world. The next sixteen years will see a huge increase in rural-to-urban migrants in search of better jobs, education and opportunity.

While the world's urban population is growing, its rural communities are shrinking. In 2007, for the first time, there were more people living in cities than in villages. It is estimated that 5 billion of the world’s 8.1 billion people in 2025 will be urban dwellers -- twice the number in 1990 (World Resource Institute). Where will these people live? About 40% will live in slums – with little or no access to clean drinking water and working toilets. Already, South Asia is home to half the world's poor and nearly 56% of India’s urban population lives in slums. Nancy Kete, director of Embarq's WRI Center for Sustainable Transport, and Owen Gutfreund, director of urban studies at Columbia University "are most critical of Mumbai, which hasn't embarked on any real urban planning despite an expected 1.8% annual population growth that will likely result in over 26 million inhabitants by 2025."