WASHINGTON -- President Barack Obama signed his first piece of legislation, the Lilly Ledbetter Fair Pay Act, seven years ago today, which made it easier for women to sue over gender-based pay discrimination. But momentum to pass more aggressive legislation has stalled in Congress, leaving it to the states to figure out how to further eliminate pay disparities between men and women.

The median yearly wage of a woman working full-time in the United States is about $39,600, which is just 79 percent of a mans median earnings of $50,400. (The gap is even more pronounced when comparing Latinas and black women to white men.) Economists say some of that disparity can be explained by employers paying women less than men for the same work.

Democrats in Congress have pushed other measures to ameliorate pay discrimination since the Ledbetter Act was signed, like banning employers from retaliating against workers who share salary information with each other, imposing harsher penalties for pay discrimination and requiring employers to demonstrate that wage gaps between men and women doing the same work are based on factors other than gender. But Republicans have repeatedly blocked the Paycheck Fairness Act in the House and the Senate , arguing the bill would discourage businesses from hiring women out of a fear of being sued.

Republican women in the Senate introduced legislation last year to make it illegal for employers to retaliate against employees for talking to each other about their salaries, but Democrats opposed isolating that element from the rest of the legislation they want to pass.