The Biggest Boomtowns

This year, for the first time, more people live in cities than in rural areas. And, increasingly, those cities are gigantic. The United Nations counts 19 megacities —  or those with more than 10 million people — throughout the world. In 2025, it expects to see eight more join their ranks: Chennai, Guangzhou, Jakarta, Kinshasa, Lagos, Lahore, Paris, and Shenzhen.

In this year’s Global Cities Index, cities in rich countries overwhelmingly outperform their counterparts in poorer countries in cultivating global ties. Three of the top 15 cities are megacities from developed countries; six of the bottom 15 are megacities from the poor world.

Urbanization can help cities that have already become wealthy climb higher, while anchoring down those that have the unlucky fate of being located in a poor state. Part of the problem is a vicious, reinforcing cycle: The challenges any large city faces — how to deal with sanitation, education, infrastructure, crime, and taxes — are much easier to solve with cash in the bank and well-trained officials at the helm.

However, a few of these developing-country megacities are breaking out of that cycle and figuring out how to make urbanization translate into globalization, while several others teeter on the edge:

Beijing (#12)
Long in Shanghai’s global shadow, Beijing’s successful Olympic spectacle earned it much international respect. In this year’s index, the city scores as the highest-ranking megacity from a poor country. But Beijing isn’t stopping to take a breath: Among other projects, it has announced a new bullet train to Shanghai, which, when completed in 2013, will be the fastest in the world.

Buenos Aires (#33)
A cultural hub of the Americas, Buenos Aires is intent on showcasing elegant design in planning the city’s future. It invests $25 million each year to promote industrial design, urban planning, and the arts. The city has seen a construction boom since the dark days of Argentina’s debt default, and it continues to draw prominent engineering and software firms. One problem city planners will need to solve as its wealthier population booms? Traffic.

Mexico City (#25)
Deadly drug violence has plagued the city in recent months, prompting an anticrime rally of 150,000 people in August. Its landfills are overflowing. And now, engineers are trying to avert an even worse threat: Low-lying slums, the old historic district, and the city’s subways could be flooded with raw sewage from its crumbling drainage system.

Dhaka (#56)
With massive traffic jams and sewage-filled rivers, Dhaka could arguably be a test case of a megacity gone wrong. Local papers recently reported that coordination between city planners was so poor that newly constructed roads had to be torn up because they forgot to run the water, sewer, and gas lines first. The good news for Dhaka: There’s likely nowhere to go but up.