Intergenerational upward economic mobility—the opportunity for children from poorer households to pull themselves up the economic ladder in adulthood—is a hallmark of a just society. In the United States, there are large regional differences in upward social mobility. The present research examined why it is easier to get ahead in some cities and harder in others. We identified the “walkability” of a city, how easy it is to get things done without a car, as a key factor in determining the upward social mobility of its residents.