The gender pay gap is shrinking, but at this rate, it might not vanish until 2070.

Women in the U.S. on average earn $0.79 for every $1 their male colleagues make, according to a new report by the job search and salary tracker site Glassdoor. The study, released Tuesday, calculated the adjusted pay gap, which accounts for variables like age, education, and industry, at 4.9 percent, down 0.5 percent from three years ago. Meanwhile, the unadjusted pay gap in the U.S. is 21.4 percent, and while that figure has shrunk by 2.7 percent since 2016, it won't fully close for another 51 years unless employers do more to fight pay disparity.

The report comes before Equal Pay Day on April 2, a date determined by the National Committee on Pay Equity that symbolizes how far into the year women must work to earn what men made in the previous year. The study looked at more than 510,000 anonymous salary reports on Glassdoor between January 2016 and December 2018.

"Companies and employers should take a stance against the pay gap," says Alison Sullivan, a career trends expert at Glassdoor. "If nothing else changes, and this shrink continues, then possibly by 2070 we could see the pay gap close."

Glassdoor offers a free audit tool to help employers determine if they have a gender wage gap, but there are other ways to eliminate salary disparities.

Instating pay transparency policies, such as publishing salary ranges on job listings or being up front about compensation with job candidates early in the interview process, can ensure fair pay between different genders and races, according to LinkedIn's 2019 Global Talent Trends report. It can also streamline negotiations and assure that interviews focus on other subjects besides salaries. Other companies are taking more active and expensive approaches: In 2016, Salesforce announced it spent nearly $3 million to cancel significant differences in pay for 11 percent of the company's 25,000 employees. 

"Whether you're large or small, there are things you can do to address the gap or have more conversations about pay transparency," Sullivan says.