Delmy Lemus, a housekeeper at the Harvard-owned DoubleTree Suites hotel, has been fighting to join a union for a year and a half. (Photo by Jonathan Wiggs/The Boston Globe via Getty Images)

CAMBRIDGE, Mass. — A couple of miles from the campuses of Harvard and MIT, in a curl of parkways and railroads, the 308-room DoubleTree hotel towers over the Charles River. The lobby inside is gleaming and vaguely academic, with vintage books artfully placed on wall shelves and abstract sculpture hanging from the ceiling.

Upstairs, starting at 3 in the afternoon and continuing late into the night, Delmy Lemus races to clean 14 large suites. Making two beds each, plus sometimes a roll-away and a sofa bed that take all her strength to pull out, she barely has enough time to finish.

“Sometimes when you are running, running, to do the work, you can’t do a hundred percent,” said Lemus, 33, who’s been a housekeeper there for six years. Once, she tripped and fell and broke her nose, while running in between rooms. Before that, she had worked more than eight months into a pregnancy, wedging her growing belly between beds and the wall, because she couldn’t afford to take time off.

Ultimately, Lemus hurt her spine by bending over while pregnant, and had to take three months off on a disability claim. (She said the insurance offered through the hotel is too expensive.) “It was so hard, so painful,” Lemus said. “When you are pregnant, your body is very tired, and you need the job to pay rent.”

But Lemus knows not all housekeepers have it so hard, including some of her colleagues who perform the same jobs. She’s heard from others who work at unionized hotels downtown, where the work is less brutal, and the rewards greater. The differing experiences are a stark indicator of how in an age of rising inequality, workers in similar professions can receive different wages and protections based on who they work for, and whether they’re unionized or not.

“I have a friend, they told me it’s a big difference working with a union and without a union,” Lemus said. “And they say ‘don’t stop, keep fighting, because it’s your benefits, your rights to have a better place to work.’”

Life is also a little easier for employees even within the entity that owns the building where Lemus works — Harvard University, which bought the DoubleTree in 2005 and now uses it to host conferences and give alumni discounts.

People who work in food service at Harvard, both employees of a contractor called Restaurant Associates and those employed directly by the school itself, are members of UNITE-HERE Local 26. After two years, the union said, they earn $21.73 per hour on average, while for many years the DoubleTree housekeepers earned only about $15 an hour. Last year, housekeepers at the hotel mounted a push to join Local 26 as well. Hilton, which owns DoubleTree, bumped salaries to $18 an hour — but has so far managed to avoid a unionized workforce.

Despite the salary increase, the DoubleTree workers still trail Harvard’s own employees in benefits. DoubleTree housekeepers also make less than those who work for unionized hotels in Boston, whose contract limits the number of rooms they clean to about half of what Lemus does.

Employees at unionized Boston hotels also earn another $9 worth of benefits — contributions to a health-care plan, defined-benefit pension, housing down payment assistance, educational programs, and legal help — on top of the $18.51 they receive per hour. According to a survey by Harvard senior Gabriel Bayard, DoubleTree workers pay on the order of $280 per month for health-care coverage, while Local 26 members who work at Harvard pay $48 for a family plan.

Lemus and other workers involved in the organizing campaign think that Harvard — which prides itself on its relationships with the seven different unions that represent its various employees — should be able to tell its tenant, Hilton, to step back and let its employees organize.

“They do whatever Harvard says, because Harvard is the big boss,” Lemus said. “So why they do this? They are hiding. They don’t want to show their face.”

Harvard disagreed: Spokesman Kevin Casey says that the university doesn’t have a hand in how the hotel’s workers are treated, since they’re Hilton’s employees.

For its part, Hilton spokesman Mark Ricci said the company doesn’t believe most of the DoubleTree employees want to unionize, and contends that it provides “some of the best jobs in the industry.” And that actually may be true — some of Hilton’s own hotels in Boston are covered by UNITE-HERE’s contract as well.

This situation — in which workers in similar professions, even in the same city, can earn a wide range of wages — describes a labor market phenomenon that’s deepening inequality in America. That trend has been the subject of countless books, articles, and speeches over the past several years, as the economy has added far more low-wage jobs after the 2008 recession than well-paying ones. What Lemus has experienced is the consequence of something that’s been going on for much longer.

In September, Harvard economics professor Richard Freeman co-authored a study based on Census data looking at how wage inequality is growing. It’s basically happening in three ways: Across industries, across firms, and within firms.

About a third of the rise in income inequality, Freeman said, has happened on account of whole industries pulling apart from each other. Wages for people in education and health services jobs overall — say, Harvard’s professors and graduates from its medical school — have grown faster than wages for hospitality workers, for example.

The next dimension of income inequality growth comes when companies employing workers in the same industry start to pay different wages. That can happen when companies have different social expectations for what workers with similar skills should earn, like Harvard and Hilton; or when they have different management philosophies, like Wal-Mart and Costco. Some firms are just more profitable than others, allowing them to pay higher wages — Harvard has more money to recruit star professors, for example, which might lead to even more revenue down the road.

Finally, Freeman said, establishments within firms are paying a wider range of wages, usually because some workplaces are unionized and some are not. That describes how a Hilton housekeeper at a hotel in the Allston neighborhood could be paid a few dollars less per hour than another Hilton housekeeper who works in the financial district. “It’s almost that when you have an expanding universe,” he said, “the stars get further apart.”

In a perfectly efficient labor market, many of these kinds of differences shouldn’t occur. Workers with similar skills should be paid a similar wage. “Supply and demand is supposed to cross at a single point, and it’s not doing that, which is a puzzle,” Freeman said. So what’s going on?

The answer: Lots of things.

Partly, the divergence in wages has to do with the decline in unions, which used to be able to enforce much stronger and more narrow wage levels within sectors, keeping wages from going both very low or very high. In 1983, unions represented 15.4 percent of workers in the hospitality industry, and now it’s 8 percent.

Union density actually has risen lately in Boston, according to UNITE-HERE Local 26 president Brian Lang, who has been working to unionize the DoubleTree workers. But it still languishes at around 50 percent, with most hotel chains fighting unionization of their newer properties, since signing a contract with Local 26 can require paying out millions more per year in salary and benefits.

The other major factor, though, is something deeper and more complicated. Earlier this year, former Boston University professor David Weil described the phenomenon in a seminal book called “The Fissured Workplace,” coining a term for the growing separation between workers and the companies that ultimately control the conditions of their employment.

Here’s what this looks like in practice: Companies contract out work to other firms that compete to give them the lowest price, which means paying lower wages and little in the way of benefits. In the hotel industry, that’s happened as hotels have franchised — according to Weil, that’s happened with 80 percent of the industry — and sold off their real estate to investors. In the Harvard DoubleTree situation, the physical owner of the hotel and the operator of the hotel are different companies. Hospitality unions argue that property owners ultimately calls the shots, but they can be more difficult to pressure.

“I see Harvard as a financial institution first, and they do some educational work on the side,” says Lang, of UNITE-HERE. “At least dealing with a private equity company, they’ll say it’s a matter of the bottom line.”

But the fissuring often goes even further, with hotel operators contracting out their own services in order to cut costs. In 2009, for example, Boston’s Hyatt hotels fired all their relatively well-compensated housekeepers and replaced them with workers provided by a staffing firm, which paid near minimum wage.

When you layer those forces on top of an employment situation where way more people are looking for work than there are total jobs available — making it difficult to bargain up wages at less-generous employers — the end result is a situation where two people in the same line of work can be required to take on different occupational risks for wildly varying financial rewards.

For Lemus, and her other colleagues who have been asking the DoubleTree management for a year and a half to stay neutral while they work toward an election, it’s not only about an hourly wage — it’s about doing a job without feeling like your body will break down because of it.

Local 26’s members, for example, have the benefit of workload and safety committees where they can raise issues like how heavy the sofa beds are, and whether they might be lightened for the sake of a housekeeper’s back.

“They don’t care about the workers. they just care about the job being done,” Lemus said. “We need to feel safe working, that we are not going to have pain.”