In contrast to the four regions above, in the mid-latitude arid region, there were no
cities with populations exceeding 4 million in 1950. As the 1950 data are based on
cities from the UN’s Annual Population of Urban Agglomerations data set with
300,000 or more persons in 2018. Thus, a city that did not have 300,000 or more
inhabitants in 2018 is excluded from the data set even if its population level was over
100,000 in 1950. Based on this data, there were 34 cities with populations of
400,000–999,999 in the mid-latitude arid region in 1950, compared with 63 such
cities in upper Eurasia. Thus, in 1950, there was scope for the mid-latitude arid
region to increase its number of populated cities. The sub-Saharan Africa region did
not have cities exceeding 1 million inhabitants.
5.3.4 Urban Populations After 1950
After 1950, again using the Annual Population of Urban Agglomerations data set as
above, it is evident that the structure of urban population sizes entered another stage,
in which the upper limit will reach 40 million in 2035. From 300 to 1800 CE, cities
of 10,000 and over inhabitants had a similar pyramidal structure, but now, after
1950, the ranges within the period altered, and there were three hierarchies of large
cities: (1) cities with populations of 1,000,000–3999,999 at the bottom, (2) cities
with populations of 4 million to 9999,999 in the middle, and (3) megacities of over
10 million inhabitants at the top.
The leading regions after 1950 in terms of increases in the number and size (i.e.,
the growth of each city’s population) of large cities were monsoon Asia and the
mid-latitude arid region. Cities falling into all three of the pyramidal population
ranges increased in both of these regions, with monsoon Asia leading this process
and then the mid-latitude arid region catching up.
Conversely, in upper Eurasia and North America and Oceania, increases in
populations and the number of large cities were only moderate. Moreover, there
was a reduction in the number of cities with 4–10 million inhabitants in upper
Eurasia. Thus, the four biggest cities in this region—consisting of three megasized cities, Moscow, Paris, and London, and one smaller city, Saint Petersburg—
remained constant from 1950 to 2035. This means that the pyramidal structure was
diverging into the top four biggest cities, and lower rank cities with populations of
1,000,000–3999,999. In North America and Oceania, two mega-sized cities,
New York and Los Angeles, remained virtually unaltered although the pyramidal
structure remains evident up to 2035.
The intermediate regions (not as fast growing as in monsoon Asia and the
mid-latitude arid region, but not as fixed as upper Eurasia and North America and
Oceania) were Latin America and the sub-Saharan Africa region. However, as a
latecomer to the process, the sub-Saharan Africa region experienced a rapid acceleration in its number of large cities.
This process of the formation of megacities is illustrated chronologically and
geographically in Table 5.2. Based on the UN data set (UN 2018) (Annual
5 Regional Diversity and Sustainability of Megacities in Global Historical. . .
83
cities with populations exceeding 4 million in 1950. As the 1950 data are based on
cities from the UN’s Annual Population of Urban Agglomerations data set with
300,000 or more persons in 2018. Thus, a city that did not have 300,000 or more
inhabitants in 2018 is excluded from the data set even if its population level was over
100,000 in 1950. Based on this data, there were 34 cities with populations of
400,000–999,999 in the mid-latitude arid region in 1950, compared with 63 such
cities in upper Eurasia. Thus, in 1950, there was scope for the mid-latitude arid
region to increase its number of populated cities. The sub-Saharan Africa region did
not have cities exceeding 1 million inhabitants.
5.3.4 Urban Populations After 1950
After 1950, again using the Annual Population of Urban Agglomerations data set as
above, it is evident that the structure of urban population sizes entered another stage,
in which the upper limit will reach 40 million in 2035. From 300 to 1800 CE, cities
of 10,000 and over inhabitants had a similar pyramidal structure, but now, after
1950, the ranges within the period altered, and there were three hierarchies of large
cities: (1) cities with populations of 1,000,000–3999,999 at the bottom, (2) cities
with populations of 4 million to 9999,999 in the middle, and (3) megacities of over
10 million inhabitants at the top.
The leading regions after 1950 in terms of increases in the number and size (i.e.,
the growth of each city’s population) of large cities were monsoon Asia and the
mid-latitude arid region. Cities falling into all three of the pyramidal population
ranges increased in both of these regions, with monsoon Asia leading this process
and then the mid-latitude arid region catching up.
Conversely, in upper Eurasia and North America and Oceania, increases in
populations and the number of large cities were only moderate. Moreover, there
was a reduction in the number of cities with 4–10 million inhabitants in upper
Eurasia. Thus, the four biggest cities in this region—consisting of three megasized cities, Moscow, Paris, and London, and one smaller city, Saint Petersburg—
remained constant from 1950 to 2035. This means that the pyramidal structure was
diverging into the top four biggest cities, and lower rank cities with populations of
1,000,000–3999,999. In North America and Oceania, two mega-sized cities,
New York and Los Angeles, remained virtually unaltered although the pyramidal
structure remains evident up to 2035.
The intermediate regions (not as fast growing as in monsoon Asia and the
mid-latitude arid region, but not as fixed as upper Eurasia and North America and
Oceania) were Latin America and the sub-Saharan Africa region. However, as a
latecomer to the process, the sub-Saharan Africa region experienced a rapid acceleration in its number of large cities.
This process of the formation of megacities is illustrated chronologically and
geographically in Table 5.2. Based on the UN data set (UN 2018) (Annual
5 Regional Diversity and Sustainability of Megacities in Global Historical. . .
83