The world’s megacities are disproportionately Asian, though Asia is the least urbanized region after Africa. Seven out of the world’s ten most populated cities are located in Asia. Of the remaining ten largest cities in the world, only Mexico City and São Paulo are in the Western Hemisphere.
Tokyo is the world’s most populated city, with a population of 37,478,000. Nearly 30 percent of Japan’s population resides in the Tokyo metropolitan area. But given Tokyo’s geographical stretch — its metropolitan area encompasses around 27,000 square miles — it isn’t even one of the world’s most densely populated cities.
Unsurprisingly, four of the world’s largest cities by population are located in the two most populated countries: China and India. Most of the world’s fastest-growing cities are in Asia and Africa.
According to the United Nations, over four billion people — or 55.3 percent of the world’s population — live in what it defines as “urban settlements.” And that figure is expected to grow to 60 percent by 2030.
Definition of a City: City Proper, Urban Agglomeration, and Metropolitan Area
You might see significant variations in population estimates for a single city. And the reason is this: there is no single standard method for determining a city’s population.
There are three main ways to determine the geographical limits of a city and its population.
The first is strictly by its administrative boundaries — also known as the “city proper.” The second way of defining a city’s geographical limits also includes “urban agglomeration” — i.e. urban areas that are geographically contiguous to the administrative boundaries of the “city proper.” The third and most expansive definition of a city is that of the “metropolitan area,” which includes not just the city’s administrative boundaries and urban agglomeration, but also nearby suburbs linked to the “city proper” by a variety of factors, including commuting patterns. So, for example, the five boroughs constitute New York City proper, but the New York metro area also includes the nearby suburbs of Nassau and Westchester counties, which are connected to the city by the commuter rail lines and highways.
In general, the United Nations relies on “urban agglomeration” for an assessment it made in 2018.
The World’s Most Populated Cities
These are the ten most populated cities in the world, according to the United Nations Population Division.