Union membership helps raise workers' pay and narrow the income gap that disadvantages minorities and women. Union workers earn 30 percent more than nonunion workers, according to the U.S. Department of Labor's Bureau of Labor Statistics. Their median weekly earnings for full-time wage and salary work were $672 in 1999, compared with $516 for their non-union counterparts.

The union wage benefit is even greater for minorities and women. Union women earn 35 percent more than nonunion women, African American union members earn 39 percent more than their nonunion counterparts and for Latino workers, the union advantage totals 55 percent.