Vidal cites Eduardo Lopez Moreno, co-author of a UN Report entitled, State of the World's Cities 2008/2009, as saying:
"Research shows that the world's largest 40 mega-regions cover only a tiny fraction of the habitable surface of our planet and are home to fewer than 18% of the world's population [but] account for 66% of all economic activity and about 85% of technological and scientific innovation."The article adds, however, that mega-regions may intensify urban sprawl and social inequity.
Read the entire article: UN report: World's biggest cities merging into 'mega-regions'
Also, check out PrimeNC and America 2050 for swell maps of the U.S. as a cluster of mega-regions.
(Image borrowed from America 2050)