In 1950 the world contained exactly two cities of more than ten million people, and neither would have surprised anyone: New York and Tokyo. The rest of the urban premier league was short, rich and mostly Western — London, Paris, Moscow and Chicago filled out the upper ranks. Within a single human lifetime that world has vanished. Today more than thirty urban agglomerations top ten million, and the table is dominated not by the old Atlantic capitals but by Delhi, Dhaka, Kinshasa, Karachi and São Paulo — places that were, by comparison, provincial towns when the century reached its halfway mark.
Cities of even one million were themselves once freakish. Ancient Rome may have touched the mark at its imperial height — historians still argue — and a handful of other cities, among them Baghdad, Chang'an and Edo (Tokyo), are thought to have reached it too in the centuries that followed, before industrialising London became the uncontested million-city of the modern age and, by 1900, the largest city the world had ever seen. In 1800 only around three per cent of humanity lived in towns and cities at all. The ten-million threshold that defines a megacity — a term popularised by the United Nations' urban statisticians — would have sounded like science fiction to any of them. The UN's demographers date the moment the world's urban population first outnumbered its rural one to around 2007: the first time in the history of the species that humanity was, on balance, a city-dwelling animal. Tokyo has sat at the top of the table for decades, its greater agglomeration counting roughly 37 million people — once more than the whole of Canada, though Canada's population has since overtaken it — though Tokyo has stopped growing, and Delhi has long been projected to take the crown before 2030.
Lagos, the city nobody can count
No city illustrates the new urban century better than Lagos. In 1950 it held perhaps 300,000 people; today the honest answer to how many live there is that nobody knows. Nigeria's last full census was held in 2006, counting heads is politically explosive because population determines federal funding and parliamentary seats, and estimates for Lagos range from about 15 million to the state government's claim of more than 20 million. What is not in doubt is the trajectory: Lagos has been among the fastest-growing large cities on Earth for decades, absorbing hundreds of thousands of newcomers a year — many into vast informal districts like Makoko, the lagoon neighbourhood built on stilts — and Nigeria is projected to become the world's third most populous country around mid-century. The city that began on an island in a lagoon, and whose name is simply the Portuguese word for lakes, now sprawls across the mainland in every direction.
The Chongqing trap
Quiz setters love the megacity table because it is booby-trapped. The most famous trap is Chongqing, in south-western China, sometimes billed as the world's largest city on the strength of a population above 30 million. The figure is real, but it belongs to Chongqing municipality, an administrative region roughly the size of Austria, most of it farmland, mountains and smaller towns; the contiguous city holds a fraction of that number. The same definitional quicksand explains why rankings never agree: a city proper (the administrative boundary), a metropolitan area (the commuting zone) and an urban agglomeration (the continuous built-up area) can give wildly different populations for the same place. Tokyo, Jakarta, Delhi and Manila all shuffle positions depending on which yardstick you pick — so the only safe pub-quiz answer is to ask which definition the question-setter means.
The deeper shift is in where the growth now happens. The first wave of non-Western megacities arrived in the 1970s and 1980s, when Mexico City and São Paulo joined the club — and for a time Mexico City was widely tipped to become the largest city on Earth, a reminder that urban projections have a habit of misfiring. The giants of Europe and North America, meanwhile, have largely plateaued: New York, London and Paris are growing slowly if at all, and Tokyo's population has begun to drift downwards. Nearly all the urban expansion of the coming decades is expected in Asia and Africa, much of it in cities many Westerners would struggle to place on a map — Kinshasa, Dar es Salaam, Ahmedabad, Luanda. The UN has projected dozens of megacities by mid-century, with African cities the fastest risers of all.
The nineteenth century belonged to London and the twentieth to New York. The twenty-first, on the numbers, has already been claimed — by cities the rest of the world is still learning to count.
Quiz nuggets
- In 1950 only two cities — New York and Tokyo — had populations above ten million.
- A megacity is conventionally defined as an urban agglomeration of more than ten million people.
- Tokyo's agglomeration, at roughly 37 million people, has long been the world's largest — once more than the whole of Canada, whose population has since overtaken it.
- Chongqing's figure of over 30 million refers to a municipality roughly the size of Austria, not the contiguous city.
- The UN dates the moment urban dwellers first outnumbered rural ones worldwide to around 2007.