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Following my recent post about the largest cities in the world (from 100 to 2015 CE), a number of you rightly pointed out that the data looked questionable. Where, for example, is Shanghai in this latest list of largest cities? So I think it's important that I do a follow-up post.
There are a number of nuances to consider when trying to measure urban populations. Perhaps the two most obvious are the geographic extent of each city (i.e. what urban boundary do you use) and the number of people living in informal settlements.
The UN recently estimated that there are some 1 billion people living in slums or informal settlements. That represents nearly a quarter of the world's urban population, which is a staggering number and a pressing global need. We desperately need more housing.
When it comes to measuring the size of an urban agglomeration, most of the studies that I have seen tend not to focus on municipal boundaries ("city propers") or metropolitan areas. The former is often based on arbitrary political boundaries and the latter often contains undeveloped rural land.
So for the purposes of this post, I'm going to go with Demographia's definition of "built-up urban area." They define this as being a continuously built-up area with one labor market and with no rural land. In their view, the world is either urban/built-up or rural. The built-up part is the lighted area that you would see on a nighttime satellite photo.
Given this definition, there are a number of interesting fringe cases. For example, contiguous/adjacent urban areas with more than one labor market get split up into multiple ones. This is the case in the US with the northeastern "megalopolis" that runs from Boston to Washington.
Conversely, if adjacent urban areas share a labor market and are linked together by similar commuting flows, then they get grouped into one urban area. This might be the case even if the area(s) straddle a national border. In this particular case, the free movement of people and goods would be another prerequisite.
With these definitions out of the way, below is another stab at sharing an accurate list of the world's largest megacities or built-up urban areas. This is one is by Demographia and there are a number of key changes compared to the last one I shared. Shanghai now features in the top 10. But Lagos drops down to number 20, which remains a bit of a question mark for me.
For a copy of Demographia's full report, click here. It looks at all urban areas with a population greater than 500,000 people (total is 985). Of course, if any of you have any other data sources that you think I should take a look at, feel free to share them in the comment section below.
Well here are some interesting figures (via MIT Technology Review):
In the past two decades, about 400 million people moved into China's cities -- so more than the entire population of the United States
By 2035, about 70% of China's entire population is expected to be urban (up from 60% today and up from 30% two decades ago)
To accommodate this scale of growth, China's national urban development approach has shifted to something that now revolves around city clusters, or megalopolises (term coined by French geographer Jean Gottmann back in the 1950s to describe the Boston-Washington corridor in the Northeastern US)
By 2035, there are expected to be five major city clusters (see above)
One of the reasons for this is to improve cooperation across the various clusters -- less competition and less redundancy
But it's also about creating smaller more manageable cities -- is this what one needs to do after a certain scale, go polycentric?
To service these clusters, China is rolling out a network of 16 new high-speed rail lines
By 2035, China expects to have 200,000 kilometers of rail, with a third of it being high-speed -- assuming this happens, China will be home to 60% of the world's high-speed rail coverage
Current cost estimates for the construction of this network comes out to about US$150 million per kilometer
1-2-3 Rule: The plan is that everyone should be able to get around a city within 1 hour; a city cluster within 2 hours; and travel between the country's clusters inside of 3 hours
China is building.
Here is an excerpt from the New York Times:
“For too long architectural elites and bureaucrats have derided the idea of beauty, blatantly ignored public opinions on style, and have quietly spent taxpayer money constructing ugly, expensive, and inefficient buildings,” Marion Smith, the group’s chairman, wrote in a text message. “This executive order gives voice to the 99 percent — the ordinary American people who do not like what our government has been building.”
As you can imagine, this proposed order isn't sitting well with many architects (the real kind who, presumably, hold licenses). Thom Mayne of Morphosis put it well with this quote:
“We are a society that is linked to openness of thought, to looking forward with optimism and confidence at a world that is always in the process of becoming. Architecture’s obligation is to maintain this forward thinking stance.”
I think there are many people who would tell you that they prefer classical architecture to modern architecture. And that's totally fine. I don't know how many is many, but I am fairly certain it is not 99% of all Americans. (It would be interesting to know the approximate taste split.)
My strong view is that I don't see the need to mandate a particular architectural style. Let architecture respond to the world around us. Let urban context guide. Like Mayne, I am also drawn to the future, as opposed to the past -- though I certainly appreciate history.
What is your view?
As a side note, classical architecture was used pretty much exclusively for federal buildings up until the 1930s. Architecture school taught me that it was initially chosen because it was seen to embody the ideals of the American democracy.
Photo by Caleb Perez on Unsplash
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