Using U.S. Census data for 1990 to 2000, we estimate effects of NAFTAon U.S.wages.We look for effects of the agreement by industry and by geography, measuring each industry's vulnerability to Mexican imports and each locality's dependence on vulnerable industries. We find evidence of both effects, dramatically lowering wage growth for blue-collar workers in the most affected industries and localities (even for service-sector workers in affected localities, whose jobs do not compete with imports). These distributional effects are much larger than aggregate welfare effects estimated by other authors.

The welfare effects of trade shocks turn on the nature and magnitude of the costs workers face in moving between sectors. Using an Euler-type equilibrium condition derived from a rational expectations model of dynamic labor adjustment, we estimate the mean and variance of workers' switching costs from the US CPS. We estimate high values of both parameters, implying slow adjustment of the economy and sharp movements in wages in response to trade shocks. However, import-competing workers can still benefit from tariff removal; liberalization lowers their wages in the short and long run but raises their option value.