And this is a conservative estimate. The Institute for Women’s Policy Research found that women workers in their prime earning ages between 26 and 59 years old make only 38% of what men earn if part-time work and years out of the work force due to family care are taken into account. See Still a Man’s Labor Market: The Long-Term Earnings Gap

Two decades ago, full-time women workers earned 59 cents for every dollar earned by men. The common explanation was that the gender wage gap existed because of a "merit gap." Women, this theory went, were not as educated as men, hadn’t worked as long, or were working in stopgap jobs until they got married, while men were family breadwinners. With increases in women’s education and employment, the wage gap did begin to narrow, although part of the narrowing was accounted for by declines in male wages.

But, in 1994, despite a booming economy, the wage gap widened. Worse, over the next several years women continued to lose ground. This flew in the face of the merit gap theory. More than forty million American working women were educated, experienced, and holding full-time jobs comparable to men’s. Like men, these women had families dependent on their earnings.

Why, instead of catching up, were hard-working women suddenly falling further behind? Over the course of the decade, many women’s earnings rose. Yet, on average, women’s earnings did not go up as much as men’s did. Women’s real wages grew 94 percent—while men’s real wages had grown 160 percent.