Ranked: The Most Populous Cities in the World

Mapped: The World’s Population Density by Latitude

When you think about areas with high population densities, certain regions spring to mind. This could be a populous part of Asia or a cluster of cities in North America or Europe.

Usually density comparisons are made using cities or countries, but this map from Alasdair Rae provides another perspective. This world map depicts population density by latitude, going from the densest populated coordinates in deep red to the sparsest in light blue.

Why Certain Latitudes (and Regions) Are More Densely Populated

Numerous factors affect an area’s population density. These can range from topography, or the physical terrain characteristics of the place, to more direct factors like an area’s climate, which can impact both the survivability and agricultural potential.

Political, economic, and social factors are also at play⁠—for example, there is a natural lack of livelihood opportunities in sparse areas such as the Amazon rainforest or the Himalayas.

High-resolution version

Breaking down the population by latitude, we see the population becomes more concentrated near the equator. In particular, the 25th and 26th parallel north are the most densely populated latitude circles. Around 279 million people reside in these latitude lines, which run through large countries like India, Pakistan, Bangladesh, China, the United States, Mexico, and others.

Despite their large landmasses, many of these countries do not themselves have very high population densities. Since density measures the ratio of people to physical space, countries with vast but sparse regions like China and India are less dense than imagined.

Out of the top 10 most densely populated countries in the world, only a couple can be found on the 25th and 26th parallel north⁠—Bangladesh and Bahrain. For a size comparison, Bangladesh is 1.55% the size of China, and Bahrain is only 0.01%.

The Future of Population Density Near the Equator

Looking ahead to 2100, the UN projects that the global population will rise to almost 11 billion. This would increase global population density from 59.11 people per square kilometer in 2022 to 80.82 per square kilometer in 2100.

However, the projections show that Asia will not be the biggest contributor to this growth. Instead, the most considerable jump in population is predicted for Africa, set to grow by almost 200% from almost 1.5 billion people today to 4.3 billion in 2100.

The equator runs right through the middle of Africa and crisscrosses countries like the Congo (both the Republic and DRC), Kenya, Gabon, Uganda, and Somalia.

As Africa’s population expands, this means that at latitudes near the equator, there could be even higher population densities coming. Or course, this largely depends on how the world’s fastest growing cities⁠—most of which are in Africa⁠—shape up over the coming decades.

The Yuxi Circle: The World’s Most Densely Populated Area

If you wanted to capture over 55% of the global population inside a circle with a 4,000km radius, which city would you place at its epicenter?

In 2013, a post appeared on Reddit marking a circular area of the globe with “more people living inside this circle than outside of it.” The circle had a radius of 4,000 km (just under 2,500 miles) and was named the Valeriepieris circle after author Ken Myers’ username.

Acknowledging that the Valeriepieris circle is not actually a circle (it was drawn on a two-dimensional map rather than a globe) and is based on data that has become outdated, mapmaker Alasdair Rae went digging and discovered what he calls The Yuxi Circle, the world’s most densely populated area.

Introducing the Yuxi Circle

Rae traced circles around 1,500 cities worldwide to find out how many people lived within a 4,000 km radius, just like the original Valeriepieris circle. He based his calculations on WorldPop data from 2020, based on a global population of 7.8 billion people.

Of the 1,500 circles that Rae made calculations for, 148 contained populations of 4 billion or more. He found many examples in Asia including in China, Myanmar (Mandalay), Laos (Vientiane), Bangladesh (Chattogram), India (Agartala), Bhutan (Thimpu), and Vietnam (Hanoi) to name a few.

But of them all, Yuxi, a city in the Yunnan province of China, has the largest population living within a 4,000 km radius: 4.32 billion.

Put another way? The circle encompasses over 55% of the world’s population, despite including desolate areas like the Taklamakan Desert, the Tibetan Plateau, Mongolia, and Southern Siberia.

Densely Populated Areas Around the Globe

Rae’s search for densely populated clusters also turned up notable circles beyond Asia. They surrounded cities like Cairo, Paris, and Mexico City.

Note: Keep in mind that the white lines on the flat maps are equidistant circles but will only look like circles when plotted on a globe.

Circling Hanoi yields a population of 4.27 billion (54% of the global population). It was the runner up city circle in Rae’s original search.

Circling Cairo yields a population of 2.29 billion. This circle reaches most of Europe while still containing populated areas of India, Pakistan, and Africa.

Comparatively, circling Paris yields a population of 1.19 billion. This Euro-centric circle contains large tracts of water and scarcely populated islands such as Iceland and Greenland.

Across the Atlantic, circling Mexico City yields a population of 0.73 billion. It’s significantly smaller than the other circles, as the total population in the Americas is concentrated in just three countries, the U.S., Mexico, and Brazil (not included in this circle).

It’s worth noting that the Valeriepieris circle also inspired other people to look at population density in different ways. In 2015, Danny Quah of the London School of Economics looked more closely at the Valeriepieris circle and was inspired to find the smallest circle with more people living inside of it than outside. He determined that a circle with a radius of 3,300 km centered near Mong Khet, Myanmar was “the world’s tightest cluster of people.”

While the Yuxi Circle contains the largest population using Rae’s approach as of early 2022, global populations are constantly changing. Who knows where the next Yuxi Circle will be?