The big news at Slate magazine last week wasn’t anything published on its website. Journalists at the online publication, frustrated by stalled union negotiations, voted to authorize a strike against their owner, Graham Holdings Co. The vote was nearly unanimous, 52 to 1.

What’s striking about this potential strike news is that Slate has a union in the first place. The magazine was a digital pioneer, founded by Microsoft Corp. in 1996, and later purchased by The Washington Post Co., which became Graham Holdings after it sold its eponymous newspaper to Amazon founder Jeffrey P. Bezos in 2013. Throughout most of its existence, Slate’s newsroom was union-free. That changed in January when it organized under the Writers Guild of America, East (WGAE) and began bargaining for a contract.

Slate is part of the wave of union-organizing that has swept over the digital-media industry over the past three years. One by one, journalists employed by the once-scrappy start-ups and venture-capital darlings of the Internet have banded together to negotiate collectively.

Gawker Media — publisher of Deadspin, Gawker and Gizmodo — was first up in mid-2015. It was soon followed, domino-like, by Salon, Vice, ThinkProgress and HuffPost. Last year, newsrooms at Fusion, MTV News, Thrillist and the Intercept voted to unionize. This year, Slate, the Onion and Vox Media followed suit.

Some “legacy” news outlets are part of the trend, too. In January, journalists at the Los Angeles Times voted overwhelmingly to join the NewsGuild, the union that has long represented workers at news organizations, including The Washington Post and the New York Times. The 244 to 48 vote followed 136 years in which the Los Angeles Times’ newsroom was without union representation and came after nearly two decades of morale-sapping cutbacks under the Times’s previous owner, Chicago-based Tribune Publishing Co.

Earlier this month, Tribune recognized the Washington-Baltimore NewsGuild as the bargaining agent for employees of the Baltimore Sun’s suburban newspaper group. The group includes one of America’s oldest newspapers, the Capital Gazette in Annapolis, the target of a gunman who killed five in June. The New Yorker and New York magazine have also signed on with the NewsGuild.

The unionization trend draws together two of America’s most troubled institutions — organized labor and the news business. The former has been losing members for decades amid globalization, changes in the economy and “right-to-work” laws. The latter has been undermined by disruption from the Internet — including by the very digital media organizations whose employees are now banding together to bargain collectively.

The organizing trend among these newsrooms reflects the growth of digital sites into mature businesses, with huge audiences, large staffs and multibillion-dollar valuations, said Lowell Peterson, the WGAE’s executive director.

“These aren’t companies aggregating videos of cats on skateboards anymore,” he said, adding, “The business models and the staffing models have stabilized to the point where people think, ‘I can make a career out of this.’ And the next thought is, ‘How can I make my career better?’ Collective bargaining is a way to improve careers.”

Indeed, in their formative years, digital companies had a reputation as latter-day sweatshops, with low pay and brutal hours. The somewhat exaggerated legend at Vice Media was its “22 rule”: Hire 22-year-olds, pay them $22,000 a year, and work them 22 hours a day.

But that was then. Under the labor agreement ratified in 2016, full-time employees at Brooklyn-based Vice won a 29 percent pay raise over three years and a guaranteed a minimum salary of $45,000 per year. The contract also locked in health-care benefits, instituted a company 401(k) match and established a compensatory time-off policy for those who worked on days they were supposed to be off.

Such agreements have created a rising tide of compensation at other digital companies, according to Peterson. They’ve also been very good for the union itself: the WGAE has added about 1,500 members to its 5,000-member roster since the digital media’s unionization efforts began.

In part, the drive to sign new members has been helped by the fact that the largest digital-media outfits are headquartered in New York and Washington, two locales that aren’t subject to “right-to-work” laws. These laws prohibit unions from imposing mandatory dues on all employees covered by a collective agreement. By enabling workers to opt out of membership, union representatives say, the statutes weaken their negotiating leverage and the union itself.

The issue is at the heart of the current dispute between Slate’s newly unionized employees and its management. Employees are seeking to make Slate a “closed” shop — one in which all union-covered workers pay dues; its management is pushing for open or optional membership.

“None of us wants to strike, but it’s something we’re prepared to do when we’ve exhausted all other options,” said Mark Joseph Stern, a Slate writer who is a member of the bargaining committee. “We’re hoping against hope that management reconsiders its position. . . . We owe it to future [employees] not to set such a terrible precedent” by creating an open shop now.

A spokesman for Graham Holdings did not respond to multiple requests for comment.

The standoff at Slate reflects some of the hard bargaining and pushback from employers wary of union-organizing efforts.

At its most extreme, one publisher shut down his company rather than negotiate a union contract. Joe Ricketts, the billionaire owner of the Chicago Cubs, closed the DNAInfo and Gothamist network of sites last year after employees voted to join the WGAE (Gothamist was later sold and relaunched).

Other publishers have discouraged their employees by arguing that union contracts could impose burdensome costs. In response to union-organizing efforts last year at Vox Media, for example, publisher Melissa Bell wrote that “we are still in a precarious industry, and we want to ensure that our business remains strong and competitive by maintaining the flexibility necessary to adapt and innovate. Doing so is imperative to our ability to provide jobs and career paths to employees.”

Bell, a former Washington Post staffer, and Vox declined to comment. But despite organizing efforts, Vox’s newsroom hasn’t been spared from the vagaries of the marketplace. The company, which operates a constellation of sites that are among the most popular among news providers on the Internet, laid off about 50 staffers, or about 5 percent of its workforce, in February.

Other digital publishers with newly unionized newsrooms have experienced turbulence, too:

●Gawker — the first digital shop to gain a union contract — was effectively run out of business in 2016 by a jury that ruled in favor of former pro wrestler Hulk Hogan in his invasion-of-privacy lawsuit against the site. (The bankrupt Gawker publishing company later sold its suite of websites to Univision Communications.)

●Mic Network, whose employees aligned with the NewsGuild in March, laid off its entire staff last month. Its remaining assets were sold to another publisher, Bustle Digital Group.

●Amid stalling revenue, Vice said last month that it would shrink its workforce by about 15 percent through attrition and eliminate about half its websites.

But organized-labor advocates see little connection between unionization and business failure. “Union members want their companies strong and around for the long term,” said Hamilton Nolan, a former Gawker writer who was involved in organizing its union. He added, “I was a media reporter for a long time, too, and I saw a bunch of nonunion media outlets fail.”

Slate’s example aside, organizing efforts don’t always raise tensions between employers and employees. Exhibit A is the Intercept, the national-security news site owned by eBay billionaire Pierre Omidyar and co-founded by journalist Glenn Greenwald.

Employees at the site agreed to unionize in April 2017. They ratified a new contract, which raised salaries and expanded some benefits, this summer.

“A union gives employees a voice and protects them from exploitation, and that is critically important even if we believe we are a benevolent employer,” said Betsy Reed, the Intercept’s editor in chief. “Management and employees do not always see eye to eye on everything, but having more formal processes to facilitate a two-way dialogue has made our organization stronger.”