1. a municipal definition - the legal city if you will
2. the urbanised area, or the physical city - the built-up portion
3. the metropolitan area, which some people refer to as the influence of the city - how far out does the city go in terms of its influence, such as commuting patterns
Most of China's cities actually have a lower population than many believe. A lot of the population near large cities are still rural and the roads cannot be commuted in a short time. It seems that most of China's cities will stay in the sub-10 million range. There will be clusters of cities in an area.
Mumbai and Dehli in India have the problems if too many slums, homeless people and traffic gridlock
A successful megacity like Tokyo has affluent development and sufficient infrastructure for housing, water, sanitation, wnergy, traffic and other services. The other model of development is to have a national or regional plan to manage the growth of cities and divert growth from stressed cities to mid sized cities that can better handle the growth. Mckinsey did a study that showed that midsized cities in India and China are growing more productivelyvthan the megacities.
There can still be economic integration of clusters of cities into megaregions but the infrastructure has to be scaled effective.
Most experts rate Tokyo as the world's biggest city because of the size of the population in the larger urbanised area.
Many of the 30 million people who are said to live in the city of Chongqing are actually agricultural workers living in a rural setting”
It will probably still be the biggest in 2025, although its population is expected to scarcely increase. The UN expects it to be followed by the two major megacities in India - Delhi and Mumbai, which are projected respectively to have 29 million and 26 million inhabitants respectively by then.
And what about the cities in the country everyone is talking about - China?
Its cities are growing so fast that for the first time more than half the population live in urban areas, it was announced earlier this month.
But China's population statistics can be particularly misleading.
"Virtually overnight, Chongqing has become the largest city not only in China, but in the world," Time Magazine proclaimed in 2005.
But it wasn't true - Chongqing is not the largest city in the world, or even in China.
Professor Kam Wing Chan of the University of Washington in the United States, who has made a career out of correcting people's exaggerated claims about Chinese population statistics, explains that what China calls a municipality or city is better understood as a province.
Many of the 30 million people who are said to live in the city of Chongqing are actually agricultural workers living in a rural setting.
He says everyone just loves to think China's cities are bigger than they actually are. He has even had to correct fellow experts at a world conference on global megacities of the future.
"They were trying to paint a really doom and gloom picture of these unmanageable urban giants, megacities with a population range of 20 to 30 million people.
"They were saying China will easily have a few of those in that range, which is not true - they are just picking up on a wrong definition. That gloom and doom scenario will definitely need to be revised."
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