It took 10,000 years – a hundred centuries – for the world’s urban population to swell to three and a half billion people, its current level. As scores of headlines have noted, this means that half the world’s population currently lives in urban areas. How much longer will it take to complete this ongoing “urbanization project”?
A new working paper (PDF) by my colleagues Brandon Fuller and Paul Romer of NYU’s Marron Institute projects that the world’s urban population will reach 9.8 billion people by 2210, with nearly 87 percent of the 11.3 billion people on Earth living in cities. That urban population will be split unevenly, with just 1.2 billion people living in the cities of what we now think of as developed countries, and a whopping 8.6 billion making their homes in the cities of the developing world. These projections, based on UN Department of Economic and Social Affairs Data, are some of the largest that I’ve seen to date.
The great bulk of this urban population growth will occur in the next one hundred years, making the 21st century truly the urban century. Fuller and Romer project that the global urban population will increase from 3.6 billion to roughly 9 billion by 2110. Overall population growth – as well as urban population growth – will start to level off after that, according to their research.
In economically developed countries, this process of urban growth has already started to stabilize. City populations are projected to swell from 960 million to just 1.2 billion by 2110. Nearly all of this new urbanization will be in the developing world, where city populations will grow from 2.6 billion today to 7.8 billion by 2110 and 8.6 billion by 2210.
The graph below, from their working paper, shows us why urban expansion is a particular problem of the developing world. As they note, “the remaining process of urbanization is overwhelmingly a phenomenon of the [Less Developed Regions], and overwhelmingly a phenomenon of this century.”
These numbers make a compelling case for why city building is the most significant task we will undertake in the coming century. We will have to radically expand existing cities and build new ones to accommodate the five billion new urban dwellers in the developing world.
Fuller and Romer note that the cities of today don’t have the capacity to grow easily to accommodate these five billion new city residents. The authors calculate that these new residents would require the world’s existing cities to expand their footprint six-fold to accommodate three times as many residents. Even more extreme, the world would need 500 new “megacities” of 10 million residents to accommodate them – plus another 125 megacities to accommodate those fleeing the high-density cities that exist today. These statistics highlight just how urgent city building will become in the coming decades.
The problem, however, is that urbanization and city building are likely to occur in an environment of weak institutions and limited public-sector capacity in many of the fastest urbanizing places on earth. As Fuller and Romer remind us, “Urbanization is peaking in the developing world at a time when the capacity to govern is still in short supply,” adding that “there is little indication that government capacity will be able to increase in time to manage urban life in anything like the way it is managed in rich countries now.”
Because of this – and because entrenched interests can make it difficult to effect change, particularly in regions with weaker governments – Fuller and Romer recommend, essentially, starting from scratch. Their first principle is that, in building new cities and expanding the footprints of old ones, governments will be able to set aside public space without the messiness of eminent domain. This means, in their view, that cities could more effectively work to combat environmental degradation, poverty, and other key issues.
Their second principle suggests that setting up new cities with more functional and equitable governance can serve as a way around the ineffective and at times corrupt systems that currently govern many rapidly urbanizing parts of the world. New migrants would, by their very act of moving, essentially have the ability to opt into more well-run and efficient cities, changing the playing field of urbanization across the world.
The authors use two historical examples to drive these points home. They highlight the successes of China’s Shenzhen, which has grown into a bustling metropolis of ten million in just the last three decades alone. By building an economy and entire new set of infrastructure from such a small base, China, the authors assert, was able to overcome the inertia and entrenchment of the Mao era and create a thriving, capitalist economy.
Reaching even further back, the authors use the case of the expansion of the Manhattan street grid during the 19th century. Though the lower part of the island, even today, is the product of the informal urban planning of the colonial period, city planners imposed a far more systematic street grid for the rest of the city. The expansion plan was relatively narrow in scope, as it merely set out the lines of the streets and the public and private spaces, without designating any specific densities or uses. But it maximized the strength of New York City’s early government, taking empty space for streets by eminent domain and dictating that landowners pay for the roads that ran by their property. This forward-thinking plan, at once limited and far-reaching, is a model for cities trying to expand their footprint to accommodate new urbanites today.
Fuller and Romer's proposals, which support mechanisms for building new cities with more effective governance structures, are aimed at dealing with the problems of global slums and poverty traps that I have discussed on this site before. As I noted earlier this winter, in many poor nations urbanization is essentially concentrated on one booming mega-city, leaving a nation’s residents with effectively no choice of where to go. But expanding the number of cities, as the authors note, can effectively create more competition and better cities.
The “urbanization project” moves forward every day, adding 60 million new city residents each and every year. There’s no time to lose, and we need to start making much more effective plans for building new and expanding existing cities across the globe. Fuller and Romer provide proactive recommendations that can help future discussion and global urban policy.