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...

We extend an analytical general equilibrium model of environmental policy with pre-existing labor tax distortions to include pre-existing monopoly power as well. We show that the existence of monopoly power has two offsetting effects on welfare. First, the environmental policy reduces monopoly...

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...

We study the distributional effects of a pollution tax in general equilibrium, with general forms of substitution where pollution might be a relative complement or substitute for labor or for capital in production. We find closed form solutions for pollution, output prices, and factor prices....

We assess the concentration and duration of zero tax liabilities and of transfer receipts, using data for households with ten to forty years of observations from the Panel Survey of Income Dynamics. We find that neither is strongly concentrated. Nearly 68% owe no federal tax in at least one...