What is a megacity?

A megacity is an urban area with a population of over ten million people. In 1975, there were only four megacities – New York, Tokyo, Mexico City and São Paolo. Today, there are estimated to be 35.

Some cities that experienced rapid growth in the twentieth century, such as Tokyo in Japan, have seen their growth rates slow down. In contrast, cities like Lagos in Nigeria, which grew more slowly in the past, are now urbanising much faster.

Asia is home to 62.9% of the world’s megacities, most of which are located in India and China, the world’s most populous countries.

In 2024, most of the world’s megacities are located in NEEs. By 2050, 14 more cities are set to become megacities, with a total increased population of some 213 million people.   The new megacities are predicted to include Ahmadabad (India), Chennai (India), Chengdu (China), Dar es Salaam (United Republic of Tanzania), London (UK), Johannesburg (South Africa), Luanda (Angola), and Thành Pho Ho Chí Minh (Vietnam).

By 2050, the world’s largest megacity could emerge from current plans rather than existing cities. China intends to combine several cities in the Pearl River Delta into a massive urban area, potentially housing 120 million people. This new megacity would encompass Hong Kong, Shenzhen, and Guangzhou, creating an urban expanse 20 times larger than London and with a population 12 times greater. Many future megacities are expected in Asia, particularly within China and India.

Many of the world’s fastest-growing cities are currently in Africa, driven by high population growth and significant rural-to-urban migration. In contrast, cities in Europe, North America, and Japan typically exhibit lower growth rates.