Megacities play a crucial role in the advancement of nations. The planning and policy fields broadly define megacities as metropolitan areas meeting a 10 million population threshold. Beyond the raw numbers of population, these super-urbanized cities and regions share traits that are unique to their dynamic nature. Dozens of urban experts and international organizations have examined various facets of the megacity phenomenon, such as adverse environmental impacts, lack of shelter, and the socio-economic and health disparities of the urban poor.

In 2011, 26 cities had an urban population over 10 million inhabitants and nine of those exceeded 20 million inhabitants. These megacities, which include such places as Tokyo, Mexico City, New York City, Mumbai, Karachi, and Beijing, share commonalities between them that bridge many differences of language, geography, or political affiliation. Megacities are enormous and changing, expanding beyond city boundaries into dynamic regional entities. Current trends show that megacity growth is accelerating in Pacific Asia while declining in North America. The only two North American megacities are New York City and Los Angeles.

As world population moves from 50% to 70% urban by 2050, the policy and governance challenges from increased urbanization will become even more complex and contentious.  In 2050 how will local governments provide essential services and protect the health and safety of its inhabitants?  How will they ensure sufficient supplies of clean water and clean air? How will cities facilitate fair and just economic growth? How will they engage and educate even more diverse residents? Global city commentators paint divergent views of the cities in 2050 as unlivable places unable to mitigate the negative impacts of migrant populations displaced by rising sea levels, drought, and social conflicts or as innovative economic engines of an emerging network of global green cities. Given their prominence in national economies world leaders and urban officials will need new strategies and technologies to ensure that cities in 2050 can address the mounting pressures of urbanization.

The Metropolitan Institute has a rich tradition of studying policy issues surrounding megacities and the design of the new metropolis.