Robert Kunzig

“Historically, cities were built on rivers or natural harbors to ease the flow of goods. But these days, since shipping costs have declined and service industries have risen, what counts most is the flow of ideas.The quintessence of the vibrant city for Glaeser is Wall Street, especially the trading floor, where millionaires foresake large offices to work in an open-plan bath of information. "They value knowledge over space -- that's what the modern city is all about," he said. Successful cities "increase the returns to being smart" by enabling people to learn from one another. In cities with higher average education, even the uneducated earn higher wages; that's evidence of "human captial spillover.”