From MSNBC :
The information is available and has been since 1964, because under the Civil Rights Act of that year, companies with 100 workers or more have had to report the data on race and gender annually to the U.S. Department of Labor. The problem has been, they were not under any requirement to release that data to the public, or even to local governments such as New York.
“Transparency is key for ensuring equal pay as well as equal opportunity for workers of all backgrounds,” said Beverly Neufeld, president of New York Women's Agenda & Director of the Equal Pay Coalition NYC. “This agreement creates that and underscores just how much willing and interested leaders in government and in business can do together to address inequality in the workplace.”
And there’s a lot of inequality, especially in the higher ranks at companies where the lack of diversity is greatest.