In California, women fare a little better, making 84 cents to every dollar that men earn.
Equal Pay Day has been an important discussion on social media.
Arianna Huffington tweeted, "It's 2015 and on average, women still make 78 cents to a man's dollar."
Actress Kerry Washington said, "Ask for more. Equal pay for equal work."
Senator Dianne Feinstein tweeted, "Critics are wrong, the wage gap isn't due to women's voices. Women still make less than men working the exact same job."
San Francisco-based Gap sent a photo saying, "We're committed to equal pay for equal work."