A beachfront vacation bungalow in Quimixto, Mexico. (Alex Pulaski for The Washington Post)

U.S. companies may be touting "unlimited vacation” policies and expanding paid leave benefits to attract younger workers. But just before the long weekend kickoff to summer, two new surveys show that plenty of U.S. workers still don't feel they can use all that time they're offered — as well as an unsettling gender divide between how young women and young men take advantage of the time off they've earned.

First the good news: According to a survey of 7,331 Americans by Project: Time Off, an initiative of the U.S. Travel Association, people are reporting that they're taking a little more time away. The survey, released Tuesday, showed that vacation use rose to an average of 16.8 days per worker, up from 16.2 days the year before, and that for the second year in a row, vacation use had climbed slightly since it began tumbling around the year 2000.

Yet there's still plenty of time left on the table, as that survey and one released Wednesday by the jobs site Glassdoor reveal. Project: Time Off says the 16.8 days that workers use on average is still far less than the 20.3-day long-term average between 1976 and 2000 — and, of course, well under the 22.6 days they say they receive. Meanwhile Glassdoor's survey of 2,224 U.S. adults found that U.S. workers on average have taken just 54 percent of their allotted time.

“Americans are really bad about taking their hard-earned vacation or paid time off,” said Scott Dobroski, Glassdoor's community expert. “I say it that way because there is a monetary value here. It’s part of people’s total compensation package.”

The report by Project: Time Off — which uses an outside firm to conduct the survey but is funded primarily by the U.S. Travel Association, which would, of course, like to see people spend more on vacations — also shows that some workers are more likely to take time off than others, revealing divides along both gender and job titles.

Although there was a jump in young men's willingness to take time off — with 51 percent saying they'd used all their vacation days, compared with 44 percent last year — fewer millennial women said they were using all of the time away they'd earned. (Forty-four percent, down from 46 percent last year, said they'd taken full advantage of their benefit.)

In explaining why they weren't using all their time, young women were also more likely to say they felt guilty, replaceable or wanted to “show complete dedication." On every measure, whether it was the fear of returning to too much work or worrying that no one else can do their jobs, more young women were concerned about the effect of vacation than young men.

“Millennial women tend to have more pronounced guilt and feel they don’t want to burden people with their time away,” said Katie Denis, the lead researcher for Project: Time Off. “They’re more likely to identify with that 'work martyr' brand of thinking.” Indeed, although the data showed a similar gender divide in other age groups, Denis said, it was most pronounced among millennial women, 46 percent of whom said it was a good thing for their boss to see them as a work martyr, compared with 43 percent of millennial men and 38 percent of overall respondents.

The survey also found a divide among job title. Senior executives may say they hear more at work about taking vacation and believe their company culture supports it, but they're also less likely to actually use it. Sixty-one percent said they left some vacation time unused, compared with 52 percent of people who are not managers.

Why the number ticked up this year is not entirely clear. Denis said part of it could be because workers are receiving more time off in the first place. The average amount of time away workers earned in 2016 increased 0.7 days to 22.6 vacation days. Or it's possible that companies are recognizing the benefits of rested workers and encouraging them to take more — or that employees are feeling more confident in their job security and less nervous about taking time off.

The trend of Americans using less of the vacation time they've earned coincides with the rise in “paid time off banks,” in which companies put vacation days, sick time and personal days into one bucket, rather than a more traditional approach of offering separate benefits. In 2002, according to a survey by the human resources association WorldatWork, 28 percent of companies offered time off this way, but that had grown to 43 percent by 2016. Employees concerned about needing to reserve time for a potential illness or a sick child might be more apt to leave time off unused when the year's end comes.

Although Denis says that may partially explain why Americans continue to not use all their vacation benefit, she said the ability to work anywhere is an equally, if not more, blame-worthy culprit. The report showed that vacation forfeiters said their biggest reason for doing so was because of their fears about returning to a mountain of work.

As she puts it: “When you can see it stacking up in real time, that can be very discouraging.” Which may help explain why, according to Glassdoor, some 66 percent of Americans say they spend time working when they are on vacation, up from 61 percent three years ago.

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