Economists have long recognized that free trade has the potential to raise countries’ living standards. But what applies to a country as a whole need not apply to all its citizens. Workers displaced by trade cannot change jobs costlessly, and by reshaping skill demands, trade integration is...

After a decade in which wages and employment fell precipitously in low-skill occupations and expanded in high-skill occupations, the shape of U.S. earnings and job growth sharply polarized in the 1990s. Employment shares and relative earnings rose in both low and high-skill jobs, leading to a...