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Megacity

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A megacity is usually defined as a metropolitan area with a total population in excess of 10 million people.[1] Some definitions also set a minimum level for population density (at least 2,000 persons/square km). Megacities can be distinguished from global cities by their rapid growth, new forms of spatial density of population, formal and informal economics, as well as poverty, crime, and high levels of social fragmentation. A megacity can be a single metropolitan area or two or more metropolitan areas that converge upon one another. The terms conurbation and metroplex are also applied to the latter. The terms megapolis and megalopolis are sometimes used synonymously with megacity. The term metacity is also sometimes used to describe cities with more than 20 million people.

Image:2006megacities.PNG
Large Cities in 2006

In 1800 only 3% of the world's population lived in cities. By the 20th century's close, 47% did so. In 1950, there were 83 cities with populations exceeding one million; but by 2007, this had risen to 468 agglomerations of more than one million.[2] If the trend continues, the world's urban population will double every 38 years, say researchers. The UN forecasts that today's urban population of 3.2 billion will rise to nearly 5 billion by 2030, when three out of five people will live in cities.[3]

The increase will be most dramatic in the poorest and least-urbanised continents, Asia and Africa. Surveys and projections indicate that all urban growth over the next 25 years will be in developing countries.[4] One billion people, one-sixth of the world's population, now live in shanty towns,[5] which are seen as "breeding grounds" for social problems such as crime, drug addiction, alcoholism, poverty and unemployment. In many poor countries overpopulated slums exhibit high rates of disease due to unsanitary conditions, malnutrition, and lack of basic health care.[6] By 2030, over 2 billion people in the world will be living in slums.[7] Already over 90% of the urban population of Ethiopia, Malawi and Uganda, three of the world's most rural countries, live in slums.

The megacity is where the best and worst of cities come together. Global connectedness and local disconnectedness characterize the regions. The level of slums contrasts the global capital building capabilities. This can be viewed as one of the tensions brought about by the globalization of modern cities.

In 2000, there were 18 megacities – conurbations such as Tokyo, Mexico City, Bombay, Sao Paulo, Karachi and New York City – that have populations in excess of 10 million inhabitants. Greater Tokyo already has 35 million, more than the entire population of Canada.[8]

By 2025, according to the Far Eastern Economic Review, Asia alone will have at least 10 hypercities, those with 20 million or more, including Jakarta, Indonesia (24.9 million people), Dhaka, Bangladesh (25 million), Karachi, Pakistan (26.5 million), Shanghai (27 million) and Bombay (with a staggering 33 million).[9] Lagos, Nigeria has grown from 300,000 in 1950 to an estimated 15 million today, and the Nigerian government estimates that the city will have expanded to 25 million residents by 2015.[10] Chinese experts forecast that Chinese cities will contain 800 million people by 2020.[11]

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Megacities around the world

In 1950, New York was the only urban area with a population of over 10 million.[12] Geographers have identified 25 such areas as of October 2005,[13] as compared with 19 megacities in 2004 and only nine in 1985. This increase has happened as the world's population moves towards the high (75–85%) urbanization levels of North America and Western Europe. The 1990 census marked the first time the majority of US citizens lived in cities with over 1 million inhabitants.

Today, the largest megacity is the Greater Tokyo Area. The population of this urban agglomeration includes areas such as Yokohama and Kawasaki, and is estimated to be between 35 and 36 million. The variation in estimates can be accounted for by different definitions of what the area encompasses. While the prefectures of Tokyo, Chiba, Kanagawa, and Saitama are commonly included in statistical information, the Japan Statistics Bureau only includes the area within 50 kilometers of the Tokyo Metropolitan Government Offices in Shinjuku, thus arriving at a smaller population estimate.[14][15] A characteristic issue of megacities is the difficulty in defining their outer limits and accurately estimating the population.

The nine largest megacities, according to this criterion are:

  1. Tokyo, Japan (36,197,000) 13%
  2. New York City , (20,700,000) 25%
  3. Mexico City (19,100,000) 6%
  4. Karachi, Pakistan (18,600,000) 6%
  5. Mumbai (Bombay), India (18,100,000) 9%
  6. Delhi, India (18,050,000) 4%
  7. São Paulo, Brazil (17,900,000) 2%
  8. Shanghai, China (17,600,000)
  9. Los Angeles, USA (17,500,000) 8%

By 2050 Mumbai is projected to be the most populous region in the world with an estimated 47 million inhabitants. Tokyo is projected to follow with 40 million people.

Source: Th. Brinkhoff: The Principal Agglomerations of the World, 2006-11-22

Other megacities include.

Another list defines megacities as urban agglomerations instead of metropolitan areas [1]. As of 2007, there are 22 megacities by this definition.

United Nations projections indicate a slow down of the emergence of new megacities after 2005. However, the expansion and merging of highly-urbanized zones may remain an important trend, as typified by the following:

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