Glassdoor's data are based on a Harris Poll of about 2,000 adults, including about 1,000 full- and part-time employees who were included in the questions about vacation.
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The findings are in keeping with other research showing that Americans are likely to leave at least some of their vacation on the table, even when they are granted it.
Of course, not all Americans are even getting the option of a paid vacation. The Glassdoor survey found that 78 percent of employees surveyed receive vacation or paid time off, while the remaining 22 percent reported not getting any paid vacation or time off.
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Other researchers have found that the United States is an outlier when it comes to vacation. The Center for Economic and Policy Research, a left-leaning think tank, released a report last year showing that the United States is the only highly developed nation that doesn't require employers to offer paid vacation time.
CEPR said its analysis found that 77 percent of U.S. workers get paid vacation time, and on average those workers receive 13 days of paid time off a year.
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That's in sharp contrast to countries including France, the United Kingdom and Germany, where workers have the right to more than three weeks of paid vacation.
You don't necessarily have to move to Europe to get that kind of perk—a select few U.S. companies buck the overall trend and offer their employees unlimited vacation.
—By CNBC's Allison Linn.