This article is fascinating:
A great paradox of our age is that despite the declining cost of connecting across space, more people are clustering together in cities. The explanation of that strange fact is that globalization and technological change have increased the returns on being smart, and humans get smart by being around other smart people.
Dense, smart cities like Seattle succeed by attracting smart people who educate and employ one another.
A person’s earnings rise by more than 7 percent as the share of people in his or her metropolitan area with a college degree increases by 10 percent, holding that person’s own level of education constant. Educated neighbors are particularly valuable in dense cities, where contact is more common.
Skilled people have often chosen to come to already educated cities, and the share of Seattle adults with college degrees has risen to 56 percent from an already high 47 percent in 2000.