Ranking the World’s Mega-Cities by Amazing New Growth Stats
Incredible NYU Study Reveals Surprising Insights on Exploding Urban City Expansion
Being born and raised in Kentucky, my initial idea of a large city growing up was comical. I knew that Louisville, KY was no metropolis, but I was often awed by the “expansive” skylines of such mega-cities as Nashville, TN and Indianapolis, IN. On occasion, I visited larger cities such as Atlanta, GA and even Los Angeles, CA. These cities began topping one another in my internal ranking of “biggest cities I had ever seen.”
Then came China.
My family had the good fortune of working for a company with headquarters located in Beijing. Near my 16th birthday, we were invited by our company’s president to come visit him in China for a 10-day “once-in-a-lifetime” trip. Upon landing in Beijing, the former vastness of LA quickly dissolved as I was beyond impressed by the Red Dragon’s capital city. In fact, I was even somewhat intimidated. Its’ fabled history, numerous dynasties stretching back thousands of years, the Great Wall, the crazed intermingling of foot/cart/bike/car traffic at major intersections… I had just never imagined a city existed such as this.
Kentucky suddenly seemed so small. However, two of our travel companions (company co-workers) hailed from New York City. Although they were certainly enthralled by Beijing, they still granted the Big Apple with the title of “biggest city we had ever seen.” At the time I couldn’t even comprehend such a feat, but I took them for their word.
Then came Shanghai. Ha!
Shanghai was baffling. Everywhere you looked, there were “mega cranes” erecting high-rise structures. Someone told us that, in fact, one-sixth of the world’s so-called “mega cranes” were in Shanghai at that very moment just to build out the city. In every direction, as far as you could see, there were high-rise buildings stretching off into the horizon. As impressive as the downtown “Bund” area was, it was Shanghai’s exterior urban/suburban extent that shook us all. It merely had no end.
As for those New Yorkers? After a few days of exploring the city, they slowly came to agree with my re-proposed question. Shanghai had indeed become the new “biggest city” they had ever seen. They were in disbelief, as we all were.
My visit to China happened 12 years ago. Since that time, mega-cities worldwide have exploded in growth at historic all-time rates. This is no cause for celebration, however, as I did not use the term “exploded” lightly. New studies continually pour in about the alarming trend of urban areas and their population expansion. For example, the United Nations reported in 2014 that for the first time in history, the majority of the world’s population now lived in urban instead of rural areas.
In today’s “big data boom,” we now have access to statistical information highlighting the rapid expansion of global mega-cities in new ways. I am fascinated in mega-cities and their impact on the future of our civilization. With that in mind, there are questions that I want answers to. This includes the following:
- Which mega-cities have grown the most in population and area over the past 10 years? 20 years?
- What is the geographical makeup of these mega-cities? Do they differ greatly by region, and if so, how?
- Are certain regional mega-cities more prone to overcrowding than others? What are the likely causes of any disparities?
Fortunately, I discovered an incredible source of new information to help elaborate on these specific questions. The “Atlas of Urban Expansion” is a multi-phase research initiative led by the NYU Urban Expansion Program, in partnership with the UN-Habitat and the Lincoln Institute of Land Policy. Their research efforts focused on creating insightful and powerful new statistics to measure 200 of the world’s largest cities by various growth trends.
With this research, we can now easily study and rank cities by expansion statistics such as population, land area, density, development and more. So, how does New York City’s growth rate differ from Tokyo? Does Paris or Manila have more developed urban land? Which global city has skyrocketed the most over the past 20 years?
I had to know the answers, so I downloaded the data. I mined the data. Then I analyzed the results with fascination. Now I am excited and ready to present you with my findings. I will do so by presenting an analysis of mega-cities and their results via the following city statistics:
- Growth by Population
- Geographic Layout (Urban, Suburban, Rural & Open Space)
- Rankings by Density (Population per Area)
I promise that you will learn something new and interesting along the way! So without further adieu, let’s dig into the numbers!
City Growth by Population: Asia Mega-Cities Are Bursting At the Seams
Simply put, Asia dominates the list of the world’s largest cities. To aid discuss and analysis, see below for the 25 most-populous cities according to the study:
Quick Impressions:
- The top 5 cities are located in Asia.
- Of the top 25 cities, 15 are from Asia.
- Most Surprising Fact: I did not expect to see Guangzhou, China ranking 2nd overall in population.
- Continental Breakdown: Asia — 15, N. America — 3, Africa — 3, Europe — 2, S. America — 2
Most of this list is not particularly surprising. It does help expand awareness of some of the urban meccas located around the world, including some which may not be on our daily radar. While some would expect Chicago to be on this list, it is out-ranked by Congo’s Kinshasa and Pakistan’s Karachi. Also, New York City is universally thought of as one of the largest cities. It tops the American charts, but its’ population figures pale in comparison to the urban sprawls of Eastern and Southern Asia.
While I find this information to be helpful, we can dig MUCH deeper to glean more relevant insights. Luckily, this study and its’ robust dataset certainly provides for more useful insights the further you “mine” the data. So, let’s take a deeper dive by asking the following:
Question #1: Which mega-cities have grown the most in population and area over the past 10 years? 20 years?
This question can provide us with an answer of action and momentum, rather than just a static number. Action is more fun than staying static, so let’s go that route.
To answer this question, the data presents us with population figures measured around these 3 periods: 1990, 2000 and 2014. The following chart illustrates the results for the current 10 most-populous cities.
Quick Impressions:
- The “blue” bar measures population at approx. 1990; the “orange” bar measures at approx. 2014
- 1990 Rankings: Tokyo was clearly #1 globally; Seoul and NYC were a distant #2 and #3; Shanghai ranked 9th; Manila ranked 14th; Beijing and Guangzhou were 21st and 52nd (!) respectively
- 2014 Rankings: Guangzhou explodes to #2 overall (!!); Shanghai and Beijing climb to 3rd and 5th respectively; Manila ascends to 8th; NYC falls to 9th place; Mexico City climbs to 10th ranking
- Off-the-Charts Big Drops: Los Angeles fell from 5th place (1990) to 13th place (2014); Buenos Aires dropped from 7th (1990) to 17th (2014); Paris falls from 13th (1990) to 21st (2014)
To further show the significant growth changes in our current largest cities, see the “temperature” chart below.
This visual aid shows the rapid growth rates experienced by the emerging Asian mega-cities. Guangzhou went from having the lowest population among the group (1990) to the 2nd-highest (2014). Shanghai and Beijing have experienced similar striking population growth. Also noteworthy are the groupings of blue in the 1990 column and red in the 2014 column. With the lowest population figures among the group in blue, and the highest among the group in red, you can see that our urban centers are skyrocketing ever upwards in population as time passes.
These visuals provide the answer to my initial question from above. Let’s connect the dots:
Question #1: Which mega-cities have grown the most in population and area over the past 10 years? 20 years?
Answer: Guangzhou, Shanghai and Beijing (all in China)
City Layout by Area: America Strikes Back!
I find this next bit of data to be the most interesting of all. Sit back and think about your city’s landscape. It generally consists of urban development, suburban living and rural space. Your city’s downtown is its’ urban center, a mix of government buildings, corporate headquarters and the core labor market. The downtown district is likely surrounded by suburbs, allotting residential living space to citizens. Meanwhile, the outskirts of a city tend to provide rural space for industrial development, protected land, etc.
The combination of urban, suburban and rural area makes up a city’s Built-Up Area. This can also be described as land development. Companies, restaurants, neighborhoods, groceries, skyscrapers, shops, utility providers, etc. all come together to define how well developed, or built-up, a city is.
In the meantime, city’s also have Open Space. These are areas such as parks or undeveloped land, which serve to connect each urban dwelling to one another within the city’s limits.
Finally, you combine a city’s Built-Up Area with its’ Open Space to determine its’ total land area. In terms of this study, a city’s total land area is defined as its’ Urban Extent.
To recap: Built-Up Area + Open Space = Urban Extent. Pretty cool, right?
With this understanding in hand, let us flesh out the research by presenting city layout data with these helpful measures. But first, I present to you my next question:
Question #2: What is the geographical makeup of these mega-cities? Do they differ greatly by region, and if so, how?
The results are shown below in a progression of visual aids and discussions.
Urban Extent
First, I present a ranking of cities by their Urban Extent, i.e. “Total City Area”:
Quick Impressions:
- The United States makes a comeback here! American cities take 5 of the top 10 spots and 7 of the top 25. This is a stark contrast to the population table earlier.
- Cool fact #1: New York City is BIG. In fact, it’s land area is equal to that of Chicago (#2 overall) and London (#18) COMBINED!
- Cool fact #2: Of all cities to be listed, I would have never guessed Minneapolis, MN to make an appearance. Curious! 🙂
- Asian cities are still very large, but their city limits do not stretch out as far as cities on U.S. soil. Perhaps this is due to America being a newer country built with sprawling cities, expansive suburbs and car transportation in mind.
The best way to understand this is by seeing it on a map. Refer below to the study’s defined urban extent for New York City, Tokyo and Sao Paolo:
The dominant colors used in these maps are purple and green. Purple represents sub-category #1: Built-Up Area. Green represents sub-category #2: Open Space. Together, they form the geographical picture of these cities. In mathematical terms, see the formula below:
Built-Up Area + Open Space = URBAN EXTENT
Urban extent is the total. But how do cities differ in their ratio of built-up developed land to open undeveloped land? That is what I want to know, so that is our next step!
Built-Up Area
Let’s break that total area shown above into its’ first sub-category: Built-Up Area. “Built-Up Area” is the developed land in a city, and it can be broken down into the following land types: urban, suburban and rural area. First, let us discuss the” “Built-Up Area” statistic. This term has a long history as it dates back to the Roman empire. Newly-built cities were defined by the edge of its “built-up area,” a.k.a. its’ extrema tectorum.
Built-up area is what gives a city its’ identity, or character. New York City is famous for Times Square, arguably the world’s most iconic urban area. Las Vegas’ “The Strip” is home to more hotels and casinos than you can count. The Italian capital of Rome is defined by the Colosseum, located in the heart of the city. These are all good examples of urban built-up area. Speaking of which, let me further breakdown “Built-Up Area” into three classes:
Urban, Suburban & Rural Area
I described urban space up above. Meanwhile, cities consist of more than just urban areas. Cities are occupied by citizens, who live in residential areas. These living spaces consist of neighborhoods, apartment complexes, groceries, convenience stores and other amenities needed and desired by the populous. This is what we call a suburban built-up area. The majority of these urban clusters are used for living space, but still contain a mixture of stores and commerce. A good example of this would be the “Highlands” neighborhood of my hometown Louisville, KY, the city’s most distinctive area of highly desirable living spaces, world-class restaurants and independently-owned storefronts. Madrid, Spain is also famous for its’ upscale “Barrio Salamanca” suburban neighborhood district. Paris’ Champ de Mars public greenspace connects urban living space with cultural and natural monuments of the city.
Lastly, cities have open spaces which connect the bustling developed areas with the quieter residential districts. This is known as rural built-up area. Think of city outskirt land, providing space for public parks, industrial factories and farms. See below for a slideshow of urban/suburban/rural areas from around the globe:
We have data that defines the land area of city’s by these 3 categories. This is done by breaking down Total Built-Up Area into each sub-category of 1) Urban, 2) Suburban, and 3) Rural area.
Built-Up Area: Urban
First, let’s dive into a data listing of the world’s 10 largest mega-cities by urban land area:
Check out the maps below for zoomed-in maps of built-up area for Los Angeles, Paris and Hong Kong. This shows a striking comparison between how urbanized/built-up each city is in comparison to one another. Los Angeles and Paris are substantially larger than Hong Kong in this respect.
Built-Up Area: Suburban
Next, I will dive into suburban land area. This produces a different group of leaders at the top, providing a curious contrast between the urban clusters of above and the vast suburban expanses of the cities below. These are the world’s 10 highest-ranking cities in suburban area:
You now see the Chinese mega-cities taking the lead here. As these cities’ populations grow at skyrocketing rates, they are having to accommodate by expanding their residential offerings. See below for another map comparison of suburban city layouts. This time I am focusing on Beijing, Chicago and Mexico City:
Case Study: Suburban Land Change vs. Population
While I analyzed the data on suburban land, I found some interesting statistics and trends. Therefore, I have chosen to present a brief yet interesting case study on 5 random cities, as listed below. Each one stands in contrast to the others and helps to highlight various growth trends that each city is experiencing. See below for the chart, and then my quick analysis points afterwards.
Analysis Point #1: Raleigh, NC residents have ample room to stretch out
This is a good example of a typical large US city. Raleigh’s population barely tops 1 million people, which is nowhere near the California mecca of Los Angeles. Yet Raleigh actually has the most suburban land of any city listed. It has experienced a growth rate of 427% since 1990, yet still maintains a relatively low population figure. This means that residents of Raleigh have more developed suburban land to sprawl out and live in, while also sharing that land with far fewer people than in LA. This “horizontal living style” is a boon for quality-of-living there.
However… Raleigh residents apparently do not handle snowfall well at all. Even if it’s only 2 inches of snow. Don’t believe me? See the results for yourself:
Analysis Point #2: Hong Kong’s Population vs. Suburban Area is frightening
I specifically chose Hong Kong for this case study, as its’ geographical makeup is very different from American cities. Hong Kong houses millions of citizens within a very small urban “island” setting. This packs in tons of people into a very small space, leading to more residential high-rises and a “vertical living style” for residents there. Compare the suburban area of Hong Kong to Le Mans, France. Hong Kong’s land is only 1.5x bigger than that of Le Mans, but Hong Kong’s population is a whopping 24x bigger!! Talk about disparity.
Analysis Point #3: Los Angeles and Osaka experienced reductions in suburban land
Most cities among the 200 studied by NYU realized positive suburban land area gain, but LA and Osaka are two cities that did not. LA, which ranked 6th in 1990 in suburban land, fell to the 19th spot in 2014 as other cities rapidly surpassed it. Osaka’s 36% reduction is even more striking, especially considering that it has a large population crammed into a smaller residential setup. Likely reasons for these reductions could be conversions to urban or rural land, but they are still curious trends to ponder.
Built-Up Area: Rural… & Open Space
With that behind us, let us wrap-up this section by discussing rural area and open space. These are city sections with low development/built-up zoning and instead give the city “room to breathe.” These spaces connect the urban and suburban land together and stretch out to form the city boundary line on its’ outskirts. I combined rural area and open space together for data comparison sakes.
See below for the world’s 10 cities with the highest combined rural area and open space:
The cities themselves are not too different here, as most mega-cities strive to have a healthy balance of urban development, suburban living and multi-purpose open space. Philadelphia makes the highest jump, up to #3 overall, which is highlighted in one of the maps below. A surprising observation is the noticeable absence of Los Angeles from this list. In fact, LA was also missing from the suburban area “top 10”. Look back to the urban “top 10” list and LA ranks very high. However, it has fallen behind other global mega-cities in suburban land development and open space creation. In the end, though, I do not have pity for Los Angelinos as they have the beach right outside their doorstep.
Yet again, I have highlighted three cities to compare and contrast in this measure. Coming up are open space/rural maps for Philadelphia, USA, Johannesburg, South Africa and Quito, Ecuador:
Hopefully you can see how cities can be measured not only by their population. Rather, the makeup of its’ land also matters. Cities with large amounts of land grant their populace with more room to spread out and live peacefully. Meanwhile, urban-heavy cities tend to constrict their populace more by jamming more people into smaller space. This leads to the differences in city identity and character, from the slow bustle of Raleigh, NC to the sky-high residential living of Hong Kong, China.
To wrap-up this section, let’s re-visit my previous question:
Question #2: What is the geographical makeup of these mega-cities? Do they differ greatly by region, and if so, how?
Answer: Mega-cities are generally organized by urban, suburban and rural land. City geographic layouts differ greatly from one another, due to factors such as economic markets, natural resources/barriers, and the needs of its’ populace.
For more insightful city maps from the Atlas of Urban Expansion project, click here. There you will find more detailed findings on all 200 cities included in the study. Trust me, it is well worth your time!
City Rankings by Density: Shifting Our Gaze to India
When we covered the largest cities by population, Chinese mega-cities topped the list. The next area of focus was ranking cities by built-up area, which was dominated by American cities. In this final major statistical comparison, we will be comparing cities by density. You will see that the category “winner” here is India.
First, I will define what these density statistics refer to. Per the Atlas of Urban Expansion 2016 Volume 1, city density, “measures the intensity of use of the urban extent or the built-up area of a city by its population.” In simpler terms, density can be explained as a simple formula:
Density = Population / Area
As a result, this will measure how crowded a populace is within its’ city limits. The importance of this cannot be understated, as the citizenry’s quality-of-life is greatly affected. This brings up my third and final question to ask on the topic of mega-cities:
Question #3: Are certain regional mega-cities more prone to overcrowding than others? What are the likely causes of any disparities?
The density statistics from this study are fascinating and worth analyzing, so I present them to you now. First, refer below for the globe’s 25 cities with the highest density ratios:
Quick Impressions
- This list resembles nothing of our first two measures of city population and city area.
- Surprising Stat: India absolutely rules this list, as 11 of the 25 cities are from there.
- Important Note: “Density: Built-Up Area” will always be higher than that of “Density: Urban Extent”. Read below to see why.
There are two density ratios presented here: “Density: Urban Extent” and “Density: Built-Up Area”. These are simple to define and help provide a relational point to one another.
“Density: Urban Extent” = Number of Citizens / City’s Urban Extent Area (a.k.a. the entire city)
“Density: Built-Up Area” = Number of Citizens / City’s Built-Up Area (a.k.a. it’s downtown/developed district)
We want to measure how dense a city’s downtown area is. We also want to measure a city’s density overall. So let’s analyze the highest-ranked city above to illustrate how this works.
Dhaka, Bangladesh has a “Density — Urban Extent” ratio of 372:1. Per hectare, there are 372 citizens residing in that small land area… that should bug your eyes out because that is very hard to imagine. Let us put that figure into context. According to a recent study from the National Association of Home Builders, the average American subdivision contains 2 houses per acre. One hectare equals 2.5 acres, so this figure converts to 5 houses per hectare. If one house contains an average family size of three people, then that equates to 15 people per hectare.
In short: the average American subdivision contains 15 people per hectare. Dhaka’s average city hectare contains 372 people.
Dhaka’s density story gets much worse when analyzing its’ “Density: Built-Up Area” ratio. It is a staggering 552:1… 552 people crammed into one hectare of land in Dhaka’s developed space. My reaction to that is the same as Keanu’s below 🙂
To elaborate on these startlingly high density ratios, I must provide a contrast to place them within context. To do so, I now present the 15 lowest-ranked cities in terms of density. Perhaps you can predict the cities most likely to appear here:
Quick Impressions
- The United States of ‘Murica stands alone at the bottom of city density rankings.
- Surprising Stat: Of these 15 cities, a resounding 12 reside in America. I would have guessed some would rank here, but not so many.
- Revisiting Raleigh: Do you remember our earlier case study of Raleigh, NC? Here are density numbers to backup what I presented there — that the citizens of Raleigh likely enjoyed a spacious and comfortable residential area to live and labor market to work at.
Standing in completely opposing positions here are the United States and India. Portland’s downtown contains 24 people per hectare of developed land, while Mumbai’s downtown area contains 369 people per hectare of developed land. Killeen’s urban extent density of 7 people per hectare is 33x less than that of Ahmedabad’s ratio. Even the highly-developed downtown of Philadelphia (5.8 million citizens) has 162 fewer people per hectare than the downtown of Indian city Jalna (278,000 citizens).
I find these statistics to be vastly fascinating and worthy of further analysis. For now, however, a simple visual aid will suffice in relating these density ratios to one another. See below for a chart depicting 5 of the highest cities and 5 of the lowest cities chosen by density, to illustrate their relation to each other:
To conclude on this topic, I must answer my previously-stated question. Before doing so, I want to briefly point out great articles on the population density issues facing Dhaka and how American cities balance the pro’s and con’s of increasing population growth. The great writers at the RISE Society and the Center For American Progress do more justice to those specific topics than I could here, so I recommend them if you are more interested in diving deeper into these topics. Based on the information presented above, I am ready to answer my question for this section:
Question #3: Are certain regional mega-cities more prone to overcrowding than others? What are the likely causes of any disparities?
Answer: Yes, cities in India and Bangladesh face significant overcrowding issues that are unprecedented. Meanwhile, American cities rank lowest in population density among mega-cities. The likely reasoning is multi-pronged; key differences are economic opportunities, improved infrastructure planning, available capital, more expansive suburban living space and natural/geographic resources.
Conclusion: Mega-City Trends Vary Wildly Across the Globe
Whew, you made it to the end! For those of you who stayed with me on this long but very interesting journey, I hope you have learning something new. I hope that you picked up a neat factoid that you can share at your next social event. Most of all, I hope you have increased your awareness of the ways that our world’s burgeoning mega-cities relate to one another. Each of them share common issues while also offering significant opportunities to their citizenry. With population growth exploding across the globe, and with more millennials seeking residence in large cities, our global urban centers must continue to adapt and react to the growth trends facing them.
Lastly, I must give tremendous praise and thanks to the talented people who created this study. Without their efforts in presenting this study and making it freely available to the public domain, my analysis of their work would not exist. I give complete credit for use of their data source, visual aids and written commentary in the following citation: Angel et al., Atlas of Urban Expansion — 2016 Edition, Volume 1: Areas and Densities, New York: New York University, Nairobi: UN-Habitat, and Cambridge, MA: Lincoln Institute of Land Policy, 2016.
What questions or comments do you takeaway from this article? Please feel free to share with me either by commenting below, messaging me on Twitter @PaulAblesCM, or emailing me at paulfpa@outlook.com. Thank you for reading!
Originally published at curiousmeasures.com on April 30, 2017.
