An increase in the share of youth in the working age population of one state or region relative to the rest of the United States causes a sharp reduction in that state's relative unemployment rate and a modest increase in its labor force participation rate. This is inconsistent with many theories of the labor market, but can be easily explained by a model of frictional unemployment with on-the-job search. The theory makes strong predictions regarding the behavior of wages which are shown to be consistent with the data. The paper also reconciles its findings with an existing body of apparently contradictory empirical evidence. # I have received helpful comments from Daron Acemoglu, Olivier Blanchard, Andrew Caplin, Henry Farber, Christopher Foote, Edward Glaeser, Bo Honore, Lawrence Katz, Alan Krueger, Christina Paxson, Harvey Rosen, Robert Topel, two anonymous referees, and many seminar participants. Thanks to Susan Gorel for providing me with cross-state unemployment and partic...

This paper explains why firms with identical opportunities may use different technologies and offer different wages. Our key assumption is that workers must engage in costly search in order to gather information about jobs (Stigler (1961)). In equilibrium, some firms adopt high fixed cost, high productivity technologies, offer high wages, and fill job openings quickly. Other firms adopt less capital-intensive technologies and offer low wages, hiring mostly uninformed workers. In equilibrium, the amount of wage dispersion leaves workers indifferent about whether to gather information, and the fraction of informed workers leaves firms indifferent about their wage and technology choice. We show that worker search, which would appear to be a rent-seeking activity in partial equilibrium, may be efficiency-enhancing in general equilibrium.

This paper argues that a risk-averse worker's after-tax reservation wage encodes all the relevant information about her welfare. This insight leads to a novel test for the optimality of unemployment insurance based on the responsiveness of reservation wages to unemployment benefits. Some existing estimates imply significant gains to raising the current level of unemployment benefits in the United States but highlight the need for more research on the determinants of reservation wages. Our approach complements those based on Baily's [Journal of Public Economics, X (1978), 379–402] test.