Americans work a lot: 47 hours a week on average, according to a 2014 survey — and a fifth work as much as 59 hours a week. Unlike other advanced nations, the annual hours we spend at work stagnated in the last half-century. So now we work more than basically everyone in the West.

But this burden is not evenly distributed. Research by the Center for Equitable Growth's Heather Boushey and Bridget Ansel, released last month, highlights something rather remarkable: access to longer hours has become a sign of privilege in American society.

The jobs where people are most likely to work over 40 or 45 hours a week are highly-paid professional positions like lawyers, business management, engineering, and finance. Low-income service jobs in health care, office support, the food industry, and the like are where people are the least likely to work long hours.

(Graph courtesy of the Washington Center for Equitable Growth.)

Since the 1980s, time at work has sharply increased for Americans with the most education, while it's collapsed for Americans with the least education.

Next, across all the surveyed professions, men are significantly more likely to work longer hours than women.

(Graph courtesy of the Washington Center for Equitable Growth.)

Boushey and Ansel cite Harvard economist Claudia Goldin's observation that "the gender gap in pay would be considerably reduced and might vanish altogether if firms did not have an incentive to disproportionately reward individuals who labored long hours and worked particular hours."

Finally, and once again all across these professions, white workers are considerably more likely to work longer hours than non-white workers.

(Graph courtesy of the Washington Center for Equitable Growth.)

So the groups working the longest hours are the ones who enjoy the most privilege: white upper-class men. That's striking, since more leisure time has traditionally been associated with privilege. As Boushey and Ansel point out, "If you Google the definition of 'bankers' hours,' it refers to the 'short working hours' bankers used to enjoy, which is certainly not the case today." In America over the last few decades, the association between leisure and privilege has been flipped on its head.

What happened?

First, we've gone through several decades now where there's basically always been more people looking for work than jobs available. Workers are competing for jobs, rather than employers competing for workers, so everyone — including professional-class white men — is worried about losing his or her job. As Boushey and Ansel write, "rising economic inequality increasingly causes workers — even those near the top of the income and wealth ladder — to feel financially insecure."

Second, the highest paying industries are also incredibly cut-throat. This brings us to Boushey and Ansel's other finding: The professions with the biggest income gaps between their lowest and the highest paid workers were also the professions where people were the most likely to work more than 40 hours a week.

(Graph courtesy of the Washington Center for Equitable Growth.)

This intra-occupational income inequality means professional offices are able to demand longer hours even from highly paid workers, and these workers are willing to oblige. Because if they don't, there are plenty of lower-salaried people just waiting in the wings to take their jobs.

This is all a pretty straightforward formula for driving hours through the roof — for the people who can actually get work.

On the other end of the spectrum, many people aren't allowed to work longer hours. Because workers can be so easily replaced, employers are free to put people to work sporadically and chaotically, especially in low-income service sectors. Racial minorities and African-Americans especially tend to be the first ones pushed into the surplus labor pool when this happens. Mothers, who still basically get no support from the U.S. government, are also forced to tap out of the workforce to take care of their children.

We used to think that as living standards improved, less work would deliver more income and thus more leisure time. But now, more and more work hours are what everyone's after. Because in today's economy, the alternative to working more isn't enjoying quality time with friends and family. The alternative is nothing. The American workplace has basically become a Thunderdome where the victors are rewarded with long hours.

The White House's decision to increase the income threshold under which workers qualify for overtime pay is a step in the right direction. More funding and staff to enforce these sorts of labor standards would also be welcome. But if longer work hours and who gets those hours is ultimately a function of a sick economy, the answer is to fix the whole thing.