Moyan Brenn / Flickr
That demographic shift means it's especially important for urban centers to start preparing for the future through infrastructure improvements, technological innovation, policy making, environmental protections and other forward-looking strategies.
A new report from AT Kearney, a global business consulting firm, ranks 125 cities based on both their current performance and their projected levels of future competitiveness. The two rankings are determined by the cities' scores across various data points - the current list factors in things like the number of political conferences a city holds and how many Fortune 500 companies it has, while the future list looks at the rate of change of indicators like patents per capita and environmental performance.
To determine the top cities of the future, AT Kearney calculated scores in four categories: personal well-being, economics, innovation and governance.
These are the cities to keep an eye on in the coming years.