Bruce Katz, Director of the Metropolitan Policy Program at the Brookings Institution, notes that roughly two thirds of America's population and 74% of it's GDP can be attributed to the largest 100 metropolitan areas.
According to Katz, intense concentration of intellectual capital and the resulting network effects are the key to modern economic growth: "It explains why Silicon Valley and Boston lead the world in technological innovation, why San Diego and Indianapolis are global players in life sciences and why Wichita, Kans., and Portland, Ore., specialize in advanced manufacturing and exports."
Katz also details the cultural and political aversion to the city: "A powerful segment of our popular culture and political leadership still paints us into the corner of quaint small towns rather than embracing a network of dominant metro economies". He does, however, note an improvement in policy under the Obama administration.
Thanks to Ryan Sloan