Clark Griswold can forget about driving all the way to Walley World. 
 
 If "National Lampoon's Vacation" had been shot today, he just couldn't have taken the time off work. That's according to data from the Bureau of Labor Statistics, which show that Americans are taking fewer, shorter vacations. 
 
 Workers pay a career penalty for vacation 
 
 Nine million Americans took a week off in July 1976, the peak month each year for summer travel. Yet in July 2014, just seven million did. Keeping in mind that 60 million more Americans have jobs today than in 1976, that adds up to a huge decline in the share of workers taking vacations. 
 
 Some rough calculations show, in fact, that about 80 percent of workers once took an annual weeklong vacation — and now, just 56 percent do. 
 
 It's not as if Americans are cutting back on an excessive vacation habit, either. The United States is the only developed economy that doesn't guarantee its workers a paid vacation. Most of its peer nations promise about 20 days off a year, according to a report by Rebecca Ray, Milla Sanes, and John Schmitt of the Center for Economic and Policy Research. 
 
 About a quarter of the American workforce doesn't get paid vacation, according to data they cite from the National Compensation Survey. The no-vacationers usually work part-time or for small employers in low-wage jobs. 
 
 The average American gets 14 days off from work, according to an annual survey by the travel company Expedia, but actually uses only 10 of those days each year. It's an open question why Americans don't use it all. They say their bosses are supportive and that scheduling got in the way. Others say they're are just stockpiling it for some future trip —but wouldn't someone, then, eventually take that trip? 
 
 One possibility is that vacation suffers from a "Prisoner's Dilemma." It's dangerous to be "that guy" who uses all the time off they get when everyone else is on the job, so workers limit their vacations. On balance, The Wall Street Journal says, the evidence does support that theory. Workers pay a career penalty for vacation. If Americans could establish a pro-vacation norm, those pressures would lessen. 
 
 That seems to be happening in some workplaces, where bosses require workers to use their time off. That might be, for the most part, just a management fad. Yet it is surprisingly normal in one industry: finance. That's not out of kindness, however. Regulators have long recommended banks require vacations as a way of making it harder to conceal embezzlement. 
 
 It's not clear what's driving the trend towards fewer, shorter vacations. Tourism tends to be very cyclical, but the decline of the great American vacation seems to have been a gradual affair. There aren't any shortage of possible explanations: lessened job security, stagnant median incomes, rising part-time employment, and an increasing share of households with more than one member employed could all be parts of the story. 
 
 There's no obvious sign that any of this has hurt the travel industry, though. Hotel occupancy is back to pre-recession highs, and employment in the leisure and hospitality industry has been one of the bright spots of the recovery. It seems like they're carrying on, Griswolds or not. 
 
 * Here's how the math works. 
 
 The Current Population Survey surveys workers once a month about a specific "reference week." If an employed person says they were absent that week — that is, they worked zero hours — and the reason why is "vacation," they're counted here. There's no reason to think that workers are more likely to take off during the survey's reference week than any other, so we can divide the number of vacation absences by the number of workers, and raise that to the fourth power to get the percentage of workers who took a weeklong vacation in one month. 
 
 Now we multiply the percentage of Americans who didn't across the last twelve months, since vacation is (obviously) seasonal. That gives you the share who haven't taken a vacation in the last year. The calculations assume that nobody takes more than one weeklong vacation each year. ||||| My wife and I returned Friday from two weeks of vacation in China, hanging out with one of our sons (posted there with the Peace Corps) and his girlfriend. We were mostly unplugged, wandered miles every day, traipsed the Great Wall and watched pandas, among other exotic (to us) exploits. And that’s what vacations are for – time away from the desk to, as an old friend once described it, get a chance to rub our fur in a different direction for a while. 
 
 Who knew we were so rare? 
 
 The folks at Vox report, based on recent federal Bureau of Labor Statistics data, that fewer Americans are taking weeklong vacations than in previous decades, for a range of reasons including fear of career repercussions to jobs that don’t offer accrued vacation days. According to Vox: 
 
 “Nine million Americans took a week off in July 1976, the peak month each year for summer travel. Yet in July 2014, just seven million did. Keeping in mind that 60 million more Americans have jobs today than in 1976, that adds up to a huge decline in the share of workers taking vacations. 
 
 “Some rough calculations show, in fact, that about 80 percent of workers once took an annual weeklong vacation — and now, just 56 percent do.” 
 
 American workers receive an average of 14 vacation days a year, according to annual studies by Expedia. The average for the industrialized world is 20 days, led by generous time-off policies in many European countries. Yet Americans last year only used, on average, 10 of their 14 vacation. Many opted to leave the days in the bank, planning to use them later on, or hoping to cash them in at retirement. 
 
 That's what vacations are for - time away from the desk to, as an old friend once described it, get a chance to rub our fur in a different direction for a while. 
 
 But others cite difficulty in scheduling the time away (conflicts with fellow workers’ time off and synchronizing vacation time with working family members), lack of money to pay for trips, and job insecurity. When it comes time for layoffs, you don’t want to be the person deemed most expendable. 
 
 Glassdoor conducted its own survey and found some different results: It says Americans took only about half of their allotted vacation time, though the reasons were similar to Expedia’s findings. When we’re on vacation, most of us still stay connected to work through email or other methods (guilty of that myself). Glassdoor found that those who reported working while on vacation cited the sense that no one could do their work while they were away (33%) and fear of falling behind (28%), among other reasons – including fear of getting fired. 
 
 And that’s not healthy. When we work all the time and skip vacations, we often become burned out, resulting in reduced productivity and increased stress that can affect our physical health and personal relationships. 
 
 Now if you’ll excuse me, I need to go check the office vacation calendar for next year. It’s never too early to plan. 
 
 Follow Scott Martelle on Twitter @smartelle. ||||| Shutterstock.com 
 
 Many Americans who are skittish about taking their vacation think they are overworked. But Chinese people appear to be even less willing to take time off. 
 
 China — which is hosting the World Leisure Games in Qingdao this weekend — has a work culture even less vacation-friendly than the U.S. Over 72% of Chinese workers have not taken a paid vacation in the last three years, according to a report by Xinhua, the state news agency, cited by the New York Times. Less than 14% of Chinese workers took a paid vacation in the last three years. Workers in China who have been employed continuously for one year are entitled to paid annual leave, according to the China Law Blog. 
 
 The situation is better — if far from ideal — in the U.S. Employees only use 51% of their eligible paid vacation time and paid time off, according to another recent survey of 2,300 workers who receive paid vacation. The survey was carried out by research firm Harris Interactive for the careers website Glassdoor. What’s more, 61% of Americans work while they’re on vacation, despite complaints from family members; one-in-four report being contacted by a colleague about a work-related matter while taking time off, while one-in-five have been contacted by their boss. 
 
 Workers appear to be getting more skittish when it comes to asking for time off. And employers too are clamping down: Summer Fridays are dead in the water, according to a 2015 survey of 15,723 Americans surveyed by Google Consumer Surveys in May 2015 for vacation site Priceline.com. 
 
 Some 40% of Americans will leave vacation time on the table, a third study found, citing a post-recession “work martyr complex” among worker who feel tied to their desk. The study by GfK Public Affairs and Corporate Communications and the U.S. Travel Association — which obviously has a vested interest in workers using up all their paid vacation time — found that one-third of the 1,000-plus respondents say they cannot afford to take their time, 40% fear returning to a mountain of work and 35% believe no one else can do their work. 
 
 Also see: The Moneyologist: How many people should go on vacation together? 
 
 This complex is reinforced by company culture and lack of encouragement from management to take time off, the GfK survey found. Even though senior business leaders overwhelmingly recognize the importance of using time off, two-thirds of American employees said their company says nothing about the need to take vacation days or discourages using them. In fact, one-third of senior business leaders state they never or rarely talk with employees about the benefits of taking time off. 
 
 Most American workers receive around 10 paid work days a year and six federal holidays, according to the Center for Economic and Policy Research, a nonprofit left-of-center think tank in Washington, D.C. So based on Bureau of Labor Statistics’ current average weekly earnings, they’re leaving more than $1,300 on the table by only taking half their paid time off. This amounts to more than $52 billion, according to economic researcher Oxford Economics, “All Work, No Pay: The Impact of Forfeited Time Off” — commissioned by the U.S. Travel Association and sponsored by American Express. 
 
 Workers in the European Union are legally guaranteed at least 20 paid vacation days a year — and 25 or even 30 days a year in some European countries. Chinese workers who have been employed between one and 10 years are entitled to five days, and entitled to two weeks between 10 and 20 years’ service, the China Law Blog notes. 
 
 People not used to taking time off may not understand that paid vacation is actually built into their compensation package. Under the The Fair Labor Standards Act, the U.S. is also one of the few developed countries that does not require employers to provide paid time off (see chart, below). Still, 91% of full-time U.S. workers receive paid vacation, according to the Center for Economic and Policy Research, but only 49% of low-wage workers — those in the bottom fourth of earners — get paid vacation. 
 
 Why don’t they take what’s due? “Fear,” says Scott Dobroski, career trends analyst at Glassdoor. “That’s the underscoring theme.” Some 28% of workers told Glassdoor they fear getting behind while they’re sitting on a beach, another 17% actually say they fear losing their job, 19% don’t take all of their days in the hopes that it will give them an edge for a promotion, while 13% are competitive and wanting to outperform colleagues. As workers shoulder a heavier workload post-recession, he says others are afraid of not meeting goals. 
 
 And that fear may not be misplaced, experts say. Citing cultural differences between Americans and Europeans is a “significant misreading” of the issue, says John Schmitt, senior economist at CEPR. “I don’t think that Americans love their families less than German or French workers who take all their vacation time,” he says. “Americans have less job security than European workers. That’s why they eat lunch at their desk and work late. And if you’re on vacation you are likely to miss important meetings.” 
 
 Most U.S. companies have an “employment-at-will” doctrine, meaning they can be fired for any reason or no reason at all, unless they have a written contract, they’re in a labor union that has other rules relating to conditions of employment or they’re fired because of some kind of discrimination. “We have almost no job security in the U.S., no legal requirement for severance pay and, with very few exceptions, can be laid off without notice,” Schmitt says. (Of course, most employees can also leave without notice, although two weeks’ notice is standard when resigning.) 
 
 “The inability to disconnect has led to a blurring of personal versus work life,” says Piera Palazzolo, senior vice president for marketing at Dale Carnegie Training. Since people take their work with them wherever they go, she says, they may simply decide to stay put. But what’s bad for the employee, she adds, is also bad for the employer. “Taking vacation is important for creativity and energy levels,” Palazzolo says. “They may be going through the motions at work, but not taking time off can lead to burnout.” In fact, more than half of American workers say just that — that they are burned out and overworked. 
 
 This story has been updated. 
 
 Other articles by Quentin Fottrell: 
 
 This is the best time to quit your job in years 
 
 How salary negotiations can earn you $1 million h 
 
 25% of firms give bonuses for incompetence 
 
 More from MarketWatch
– The US is the only developed country in the world that doesn't require its workers to have access to paid vacation. While those in the European Union are guaranteed at least 20 paid vacation days a year (and 25 or even 30 days in some countries), most Americans get about 10 paid days a year and use only half, according to a new survey reported in MarketWatch. And of those actually on vacation, 61% confess to working while vacationing, with one in four saying they were contacted by a colleague and one in five saying they were contacted by a boss. Things were apparently better in 1976 when 9 million Americans took a week of vacation in July, reports Vox. This past July, even with 60 million more Americans employed than in 1976, only 7 million took a week off. Some calculations put just 56% of workers taking a weeklong vacation in a given year, a figure that used to be as high as 80%. Top reasons for people taking less vacation time are less accrual of days and fear of hurting one's career or place at work. "That's not healthy," writes Scott Martelle in the LA Times. (Check out how many Americans don't get any paid vacation at all.)