Using a sample of Harvard undergraduates, we analyze trust and social capital in two experiments. Trusting behavior and trustworthiness rise with social connection; differences in race and nationality reduce the level of trustworthiness. Certain individuals appear to be persistently more...

Cities are shaped by transportation infrastructure. Older cities were anchored by waterways. Nineteenth century cities followed the path of streetcars and subways. The 20th century city rebuilt itself around the car. The close connection between transportation and urban form is natural, since...

When members of deliberating groups speak with one another, their predeliberation tendencies often become exacerbated as their views become more extreme. The resulting phenomenon -- group polarization -- has been observed in many settings, and it bears on the actions of juries, administrative...

Historically, urban growth required enough development to grow and transport significant agricultural surpluses or a government effective enough to build an empire. But there has been an explosion of poor mega-cities over the last thirty years. A simple urban model illustrates that in closed...