In smaller towns, cities and rural areas, the coronavirus outbreak and its aftermath have sparked a rush of news stories about people leaving big cities to start a new, healthier and less crowded life.
Because of their exceptional density and dependency on public transport, megacities in advanced economies such as London and New York are especially vulnerable to virus-induced flight.
Despite being costly and crowded, they have flourished over the past three decades because they could balance those drawbacks with superior work and income opportunities and a vibrant cultural life.
The virus has now entered the labor market and services. The consequence has been people leaving to secondary cities, towns and rural areas that offer more space and lower health risks. But there’s a more complex truth.
Megacities have always been busy, areas that are unhealthy and vulnerable to infectious diseases. London was so unhealthy in the 17th and 18th centuries that more people died than were born in the city. The city’s population only grew due to a steady inward migration from other parts of Britain.
The same was true of other historical megacities, like ancient Rome and early modern Naples, Paris, Manchester, Bombay and Calcutta, that were disease-ridden and polluted. Constant inward migration compensated for the exceptionally high rates of death, which were even higher than in smaller towns and rural areas.
Almost all megacities have similar migration systems, attracting young migrants and those from other domestic and international regions, while losing older residents to more spacious and less crowded, cheaper areas.
The Modern Megacities
Modern megacities, even though vulnerable to epidemics, are healthier. But to replace the outflow of older residents seeking cheaper housing, they still rely on a steady inflow of younger migrants, both domestic and foreign.
Over the decade and a half to 2019, London’s population grew by 1.5 million, or 21%, amid growing house prices and an increasingly overloaded transport system, as young people and international migrants poured in.
However if, in the future, the virus and the threat of other infectious diseases create demand for less density and crowding, megacities will have to compensate for that, at least, by being cheaper to live in.
The urbanization trend is still at a relatively early stage in low-and middle-income countries, comparable to the cities of Europe and North America in the 19th and early 20th centuries.
Like their European and North American forerunners, despite the epidemic, the fast-growing megacities of Asia, Africa and Latin America would probably see continued population growth.
The megacities differ from other regions in a number of ways including income and jobs, there are less resources for remote work and the population composition, which is much younger.
In spite of their health problems, the same pressures which drove migration to London, Paris, Manchester and New York between the eighteenth and early twentieth centuries will continue to drive urbanization in emerging markets.
The epidemic and its aftermath are likely to have an impact on both outflows and inflows of population from megacities at least for the short term. It is likely to increase health and crowding concerns, while reinforcing the desire for more space, which is likely to speed up the current outflow of older residents.
At the same time, downturns in economic activity and job prospects, as well as restrictions on travel, are likely to slow down the migration of younger migrants from the country and abroad. Therefore, the megacity populations are likely to decrease or at least expand more slowly in the short term than before the pandemic.
Whether the disruption of megacity population growth proves temporary or more permanent in the most advanced economies depends on how rapidly cities can restart young and foreign migrants’ inward migration to mitigate their loss of older residents.
It is clear that the easing of international quarantine restrictions and the resumption of international aviation will be crucial, as will the recovery of megacity job markets for younger workers and social facilities.
But, compared to other areas, megacities will also need to become cheaper and more affordable for a while to draw more young inward migrants and to reduce the opportunity for older residents to sell and move out.