On Tuesday, women across the nation will observe Equal Pay Day, which was created 21 years ago by the National Committee on Pay Equity. The event is held in April to symbolize the extra time women need to work to earn what men earned in the previous year.
The average American woman's salary has been found to be around 78% to 82% of that of the average man's. The gap is believed to be due to gender discrimination and a discrepancy in salary negotiation skills between men and women.
The average gap varies from state to state, as can be seen in this graph based on data collected by the US Congress Joint Economic Committee.