Between 1973 and 1988, private-sector unionism fell by 9.5 percentage
points more for men than women, and the gender wage gap (one minus the
ratio of female to male wages) decreased by .09. These trends support
two findings: First, unionism fell more slowly for women primarily be
cause the probability of unionism fell most rapidly in jobs dominated
by males. Second, the greater decline in unionism among males is respo
nsible for approximately one-seventh of the .09 decline in the gender
wage gap.