WASHINGTON — Pay disparities between men and women start earlier in their careers than widely assumed and have significantly widened for young workers in the past year, according to a new report from the Economic Policy Institute.

Paychecks for young female college graduates are about 79 percent as large as those of their male peers, the think tank found – a big drop from 84 percent last year.

The jump follows a more gradual shift. In 2000, women ages 21 to 24 with college degrees earned on average 92 percent of their male counterparts’ wages, which was unchanged from 1990.

The growing gap was driven by an 8.1 percent increase in young college-educated men’s wages since 2000 and a 6.8 percent decrease in young college-educated women’s, adjusted for inflation.

Regardless of their education, young women typically earn less money than young men in the United States. Female high school graduates, ages 21 to 24, earn an average of 92 cents for every dollar paid to their male counterparts.

Some have argued that the wage gap, at any stage of a woman’s life, starts with her choices. Women are more likely than men to scale back at work when they start a family, for instance. But the EPI data shows that the gender wage gap cracks open right after college graduation, well before decisions like maternity leave can affect women’s earnings.

The gender wage gap in the broader labor force has steadily declined since the 1980s.

“It is noteworthy that stark wage disparities between men and women occur even at this early part of their careers,” the researchers wrote, “when they have fairly comparable labor market experience.”

Young men with a college degree earn an average hourly wage of $20.94 right after graduation, according to the EPI figures, compared with the average hourly wage of $16.58 for women.