Richard Florida writes:
"Economists increasingly argue that clustering, concentration, and density stand alongside land, labor, and capital as key features that shape economic growth.
American cities account for nearly 90 percent of total U.S. economic output, and 85 percent of U.S. jobs. [...] Across the globe, metros with populations over one million account for more than half of the world's economic output and nine of every ten innovations, while housing roughly one out of every five people."
