Explaining levels of within-group wage inequality in U.S. labor markets.

Most research on earnings inequality has focused on the growing gap between workers of different races and at different education, age, and income levels, but a large portion of the increasing inequality has actually occurred within these groups. This article focuses on the extent and sources of "within-group" wage inequality in more than 500 labor markets in the United States in 1990. In addition to documenting that within-group wage inequality across regions varies more widely today than over the past several decades, the analysis reveals that two frequently cited explanations of rising wage inequality over time have little impact on within-group wage inequality when measured at the local labor market level: (1) industrial shifts and (2) increased technology and trade. By contrast, flexible and insecure employment conditions (e.g., unemployment, contingent work, and immigration) are associated strongly with high local levels of within-group wage inequality, especially among women.