Today is “Equal Pay Day,” symbolizing how far past 2016 and into 2017 women in the United States, on average, have to work to earn as much as men did in 2016. In other words, to bring home what men earn in 12 months, women have to work for more than 15 months – or until April 4.

Data from the US government showed a 20.4 percent wage gap between men and women for 2015. The median annual earnings of women who worked full-time, year-round were 79.6 percent of men’s full-time, year-round earnings that year. The gap is even larger for women of color.

A mother and her daughter participate in the International Women's Day "A Day Without a Woman" protest in Los Angeles, California, U.S., March 8, 2017.

© 2017 Reuters

Even when controlling for factors such as experience, education, industry, and hours, women and men get paid differently. An in-depth examination of the gender wage gap by economists found that discrimination plays a role.

This matters for all women but, with the aging US population, the gender wage gap especially hurts older women. A 2016 report found that women’s lower career earnings, including due to the wage gap, contributed to older women having lower social security benefits, pensions, and savings.

The 1963 Equal Pay Act and the 2009 Lilly Ledbetter Fair Pay Act have strengthened legal channels for women to claim equitable pay, but more is needed to end wage discrimination against women. An important bill pending in Congress would help women uncover and challenge discriminatory wage practices.

The Paycheck Fairness Act would increase transparency about salary information, ensure that women can access remedies available for other forms of wage discrimination, and allow victims to receive compensatory and punitive damages. It would prohibit employers from retaliating against employees who discuss their wages.

The wage gap between men and women is an affront to the values of fairness and equality. Congress should do its part to close the gap by passing the Paycheck Fairness Act.