Women in the U.S., on average, earn around 79 cents for every dollar a man makes.

Equal Pay Day, which falls on April 2 this year, is a symbolic of how far into the year women need to work to earn what men earned the previous year. It represents the uncontrolled gender pay gap — the median salary for all men and women working across industries. (When controlled for factors like job title, years of experience, industry and location, the pay gap narrows, though experts differ on how much .)

Salary comparison site PayScale found that the uncontrolled gap has narrowed 1 percent over the last year, according to their  State of the Gender Pay Gap in 2019 report. PayScale Chief Economist Katie Bardaro says this improvement may signal increased representation of women in top-paying fields.

But while there are reasons for optimism, this improvement may not be worth celebrating — at least not quite yet.

The modest improvement in the uncontrolled gap "is statistically significant, but I would say it's not closing at the rate that any of us would like," Lydia Frank, Vice President of Content Strategy at PayScale tells CNBC Make It . "And for the controlled gap, it's pretty much been stuck where it is within a percentage of a percent for a long time. I'm not terribly hopeful that there will be another percent improvement next year — it could just as easily drop down again."

Others say that a small decrease in the uncontrolled pay gap may signal that improvements are ahead.

"Year-to-year changes are based on relatively small samples, but I think it does suggest that there is this upward trend," Daniel Hamermesh , distinguished scholar at Barnard College and Network Director for the Institute for the Study of Labor tells CNBC Make It .

Hamermesh remains optimistic that significant increases in women's educational attainment will begin to pay off over the next several decades.

When the U.S. Census first started collecting data on Americans' educational attainment in 1967, about 12 percent of women and 17 percent of men between the ages of 25 and 29 held bachelor's degrees. Today, women outnumber men at all levels of education .

"Only 15, 20 years ago, the fraction of women graduating college exceeded that of men. These women are now in their middle-30s. It takes time for that whole giant cohort to work its way through the labor force," says Hamermesh, adding that he would be "absolutely shocked" if we did not see a narrowing of the pay gap in the years ahead.