These Maps Show The Exploding Urban Footprints Of The Fastest-Growing Cities

Marvel at the growth patterns for 10 of the world’s megacities, and then you’ll see why people are worried about our exploding population. Where do we put everyone?

In 1950, Lagos, Nigeria was home to around 300,000 people. By 2015, the Nigerian government estimates that the population will have ballooned to 25 million, making it the third-largest megacity in the world. A new website shows how that growth translates to sprawl on a map.


The Age of Megacities project maps out the growth of 10 of the world’s largest cities–from the fastest-growing, like Lagos, to places like London, which was once the biggest city in the world, but only officially reached “megacity” status this year (A megacity is usually a metropolitan area with more than 10 million people.)

Here’s Mexico City, growing from a tiny city center in 1910 to a sprawling blob around 100 times larger:

Almost all of the population growth in Mexico City has happened in the suburbs, leading to three-hour daily commutes, and some of the world’s worst air pollution. Now, the government is finally pushing for denser development. But similar sprawling growth is happening in other megacities, like Sao Paulo and Mumbai. Of the 3.6 billion people who live in cities, around 1 billion live in slums at city edges.

Even slower-growing Paris, which people tend to think of as a classic example of a walkable city, has sprawled dramatically in the last century:

The Age of Megacities site doesn’t include all of the world’s largest megacities, in part because most of the cities don’t have enough data to map out growth. But those that are included are an important reminder of how important urban planning is now. Since 1990, the number of megacities in the world has tripled, and by 2050, 2.5 billion people will live in cities.

Planning how those cities grow will have a huge impact on everything from health to climate change. As the Smithsonian points out:


Cities are also responsible for 70 percent of the world’s carbon emissions, especially those that sprawled outward as they grew. A 2014 study showed that in cities with large suburban zones, such as Los Angeles, the high carbon footprint of outlying neighborhoods cancels out any benefits from people living in the denser downtown area.

All of the maps on the Age of Megacities website are worth a look, if only to show what we’ve been doing wrong so far.


About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley.