City Outlook: Demographics of Interest
By 2050, the world population will increase by 2.5 billion, while the urban population is projected to increase by 3.1 billion. These increases will nearly double the world’s urban population, swelling it from 3.3 billion in 2007 to 6.4 billion in 2050. Nearly all the world population growth will be urban, while cities will continue to draw some from the rural population.
Over the next seventeen years, by 2025, small urban centers, those with less than half a million inhabitants, are expected to absorb nearly half of the expected increase in the urban population.
Cities in the next size class are those with 500,000 to one million inhabitants. In 2005, 446 of these cities existed. That number is projected to increase to 551 by 2025.
Medium-sized cities are those with more than one million inhabitants but fewer than five million. In 2005, 361 of these cities dotted the globe. This number is expected to increase to 524 by 2025.
Large cities are those whose populations range from five million to just under ten million. Thirty large cities were counted in 2007, and the number is expected to grow to 48 in 2025.
A megacity is an urban agglomeration with at least ten million inhabitants. Currently, there are 19 megacities around the world. The number of these huge urban areas is expected to increase to 27 in 2025.