7 Billion Humans | National Geographic Magazine: Crowds on the Streets of Calcutta (Kolkata) | India

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Crowds on the Streets of Calcutta (Kolkata) | India

The rapid growth of cities like Chicago in the late nineteenth century and Calcutta a century later can be attributed largely to rural-urban migration. This kind of growth is especially commonplace in developing countries. The urbanization of the world’s population over the twentieth century has been dramatic—13% of the population lived in cities in 1900, 29% in 1950, 49% in 2005, and likely 60% (4.9 billion) by 2030. According to the UN State of the World Population 2007 report, sometime in the middle of 2007, the majority of people worldwide will be living in towns or cities for the first time in history; this is referred to as the arrival of the “Urban Millennium” or the ‘tipping point.’ In regard to future trends, it is estimated that 93% of urban growth will occur in developing nations—80% of it occurring in Asia and Africa.