The Union Wage Differential

From the Bureau of Labor Statistics:

In 2012, among full-time wage and salary workers, union members had median usual weekly earnings of $943, while those who were not union members had median weekly earnings of $742. In addition to coverage by a collective bargaining agreement, this earnings difference reflects a variety of influences, including variations in the distributions of union members and nonunion employees by occupation, industry, firm size, or geographic region.