The US is marking Women's Equality Day with a pledge to close the gender pay gap.
On Friday, 29 companies joined an Obama administration pledge to take steps towards equal pay for men and women.
The White House launched the Equal Pay Pledge in June, with an invitation for businesses to commit to "conducting an annual company-wide gender pay analysis across occupations [and] reviewing hiring and promotion processes and procedures to reduce unconscious bias and structural barriers".
American Airlines, Johnson & Johnson and Spotify were among 28 businesses to join the initial pledge.
Prominent tech companies lead the 29 that pledged on Friday, including Apple, Facebook, Intel and Microsoft.
Women's Equality Day marks the anniversary of the 19th Amendment, which granted US women the right to vote in 1920.
The official day was established in 1971 after Congresswoman Bella Abzug introduced a bill to establish the day of recognition.
Women working full time in the US earn 79 percent of what men earn.
The gap is larger for black and Latina women, who earn 63 and 54 percent respectively of what men earn.