When Trade Compresses: The Impact of Liberalization on Wage Inequality

We study the effects of trade liberalization on the full wage distribution, exploiting Spain's 1993 entry into the European Single Market. Using employer-employee data, we identify the causal effects of trade across the entire wage distribution, using a novel shift-share instrument embedded in an unconditional quantile regression. We find that the liberalization reduced wage inequality, leading to wage compression through earnings gains at the bottom of the distribution and wage losses at the top. We trace this compression to two asymmetric channels: import competition disproportionately harmed high earners, while export opportunities benefited low earners. The key mechanism is an import-driven "skill-downgrading." A multi-region multi-sector model shows that the key insight for understanding these empirical results is that trade's distributional effects depend on the skill intensity of a country's tradable sector, and Spain's was relatively low-skill intensive back then.