When women started moving into the workforce in larger numbers during World War II, activists stepped up their efforts to increase pay for women workers, leading to the National War Labor Board endorsing equal pay for women who were replacing male workers who were at war. In 1945, Congress introduced the Women’s Equal Pay Act, but it failed to pass, despite valiant efforts from advocates to win support.

By 1960, some progress had been made, but women were still paid less than two-thirds for the same work. During President John F. Kennedy’s administration, things started to fall into place. Esther Peterson, who ran the Women’s Bureau of the Department of Labor, endorsed legislation to close the pay gap, as did former first lady Eleanor Roosevelt. Pro-corporate forces fought the passage of the law, but it finally prevailed in 1963.