A fact sheet by the Institute of Women's Policy Research (IWPR), issued for March 8, International Women’s Day, and based on data from the U.S. Bureau of Labor Statistics, shows that in 2011 women earned 17.8 percent less than men for a week of full-time work, a decrease of 1 percentage point since 2010, and the smallest wage gap seen since 1970.

Real earnings for both men and women have fallen since 2010, by 0.9 percent for women and 2.1 percent for men. In 2011, median weekly earnings for full-time work were $684 for women and $832 for men. This narrowing of wage inequality is due to smaller real earnings losses for women than for men.

"When the IWPR was founded 25 years ago, the weekly gender earnings gap was 30.2 percent," said Heidi Hartmann, founding president of IWPR. "Seeing the gender wage gap, an important thermometer for measuring gender equality at work and in families, fall to its lowest level ever at 17.8 percent is a sign of how much has changed during the last 25 years. Yet the fact that men's real earnings were lower in 2011 than they were in 1986, and that much of the narrowing of the gender wage gap is due to men's lack of progress, makes the lower gender wage gap less of a cause for celebration."

The gender wage gap is stark for black and Hispanic women. Black women's median full-time weekly earnings were only 69.5 percent, and Hispanic women's only 60.5 percent, of the median weekly earnings of white men. Black and Hispanic men also have substantially lower earnings than white men, although median male earnings are higher than median female earnings within each racial/ethnic group.

"The fall in real earnings is particularly hard for women of color," said Ariane Hegewisch, IWPR study director. "Their median weekly earnings for full-time work put them only marginally above the federal poverty level for a family of four."