In September 18, leaders from the International Labour Organization, UN Women, and the Organization of Economic Cooperation and Development launched the Equal Pay International Coalition (EPIC) with the goal of closing the gender pay gap by 2030—a challenge set by the UN Sustainable Development Goals.

“One of the most visible, tangible, and pervasive manifestations of discrimination is that women across the globe are still being paid less than men for work of equal value,” said Guy Ryder, director-general of the ILO.

According to an April 2016 report by the Joint Economic Committee Democratic Staff, U.S. women earn only 79 cents to every dollar earned by a man. That number is even worse for women of color—African-American women receive, on average, only 60 cents per dollar and Latina women receive only 55 cents per dollar.

Out of twenty-one countries with 2015 wage gap data analyzed by the Organisation for Economic Co-operation and Development, the United States ranks 17th.

Despite the passage almost four decades ago of the 1963 Equal Pay Act—which “prohibits sex-based wage discrimination between men and women in the same establishment who perform jobs that require substantially equal skill, effort and responsibility under similar working conditions”—the gender wage gap looms wide. Not only has the United States failed to meet its own goals, we continue to lag behind our global peers.

Out of twenty-one countries with 2015 wage gap data analyzed by the Organisation for Economic Co-operation and Development, the United States ranks 17th.

At the 2016 Republican National Convention, Ivanka Trump said of her father Donald Trump—then the Republican nominee—“He will fight for equal pay for equal work, and I will fight for this too, right alongside of him.”

Seven months into Trump’s presidency, Ivanka Trump blessed her father’s decision—based on concerns over “confidentiality” and “burdensome” regulation—to end an Obama-established rule that would have required businesses to begin collecting wage data in March 2018. The Republican-controlled House of Representatives followed a few weeks later by voting down an amendment that would have maintained financial support of the Equal Employment Opportunity Commission’s equal pay data collection initiative.

The Washington Post reported in July that the White House’s own gender-pay gap has tripled under Trump.

Mark Perry, of the American Enterprise Institute, called Equal Pay Day a “bogus feminist holiday.”

Mark Perry, the economist responsible for the numbers behind the Post’s report—who works for the conservative American Enterprise Institute think tank—ridicules the idea that “gender discrimination is the main explanatory factor for any aggregate, unadjusted gender differences in earnings,” calling Equal Pay Day a “bogus feminist holiday.”

A complex web of social and economic factors contributes to gender-based income inequality. Ryder listed a number of them: “adverse social and cultural norms; discriminatory laws and the lack of legal protection; the lack of access to financial, digital and property assets; [and] the overload of unpaid work on women.”

According to research by the Joint Economic Committee Democratic Staff, however, when other factors were accounted for, “as much as 40 percent of the pay gap may be attributed to discrimination.”

If 40 percent of the gender wage gap in the United States can be attributed to discrimination, it means discrimination costs white women 8.4 cents of every dollar earned. African-American and Latina women pay a higher price—respectively 16 and 18 cents of each of their dollars is lost to discrimination. On a salary of $50,000 a year, that’s a cost of $4,200 for white women, $8,000 for African-American women, and $9,000 for Latina women.

In a statement responding to the House vote on wage gap data collection funding, ACLU’s Senior Legislative Council Vania Leveille warned that, without transparency, “the pernicious gender and race wage gaps, and the discrimination that causes them, will continue to flourish.” It said the Equal Employment Opportunity Commission’s data collection “would have deterred intentional pay disparities, facilitated employers’ good faith efforts to comply with equal pay laws, and identified appropriate targets for federal enforcement of nondiscrimination law.”

Gender pay equality is a matter of social justice. It’s also promotes economic development, something Donald Trump says he supports. Narrowing the gender pay gap is clearly something Congress and the President should support. As Ryder put it at the EPIC launch, “It is not only a matter of the right thing to do . . . it is the smart thing to do.”