Now the case for upgrading American transportation infrastructure isn’t about short-term Keynesian stimulus. It’s about long-term growth. “Places that have the greatest accessibility, that enable more people to interact in less time, produce the greatest wealth,” write transportation experts Matthew Kahn and David Levinson in a 2011 report. More accessibility also means more economic mobility. A 2013 analysis from the Equality of Opportunity Project found climbing the ladder much harder in cities with longer commute times. Indeed, the monetized cost of US congestion is around $120 billion a year.