Rapid expansion of city borders, driven by increase in population and infrastructure development, would force city borders to expand outward and engulf the surrounding daughter cities to form mega cities, each with a population of more than 10 million. By 2023, there will be 30 mega cities globally, with 55 percent in developing economies of India, China, Russia and Latin America.
The mega cities from emerging economies will witness a CAGR of 4.4 percent in GDP (PPP) from 2009 to 2025, as compared to a CAGR of 1.63 percent for the same period in the mega cities from developed economies.
Convergence of two or more closely located mega cities will lead to the formation huge mega regions. For example, by 2020, Johannesburg and Pretoria in South Africa will converge to form one big mega region called “Jo-Toria.”