President John F. Kennedy signed the Equal Pay Act into law on June 10, 1963. The law mandates that men and women receive equal pay for “substantially equal” work at the same establishment. A year later, Congress passed the Civil Rights Act of 1964. In addition to providing protections against discrimination based on an individual’s national origin, race and religion, the Civil Rights Act prohibits discrimination on the basis of an individual’s sex.

Over the course of more than a half-century, these laws and more recent legislation have helped make it more likely that women receive equal pay for equal work. However, women still tend to be paid substantially less than men. Based on median annual earnings, a woman working full time, year-round typically earns only 79 cents for every dollar earned by her male counterpart. The 21?percent difference in earnings (or 21 cents on the dollar) is known as the “gender pay gap.”

The difference adds up—women’s median earnings are $10,800 less per year than men’s. Over the span of a career that yearly difference could accumulate to a half million dollars.

The pay gap also dramatically affects what women receive in retirement because it reduces women’s earnings. The major sources of retirement income, including Social Security and pension benefits, are largely calculated on the basis of career earnings. Income of women ages 65 and older ($17,400) is 44 percent less than the median income for men in the same age group ($31,200). As a result of this and other factors, a higher percentage of women than men end up living in poverty after age 65.