For decades, hotel workers in Long Beach, Calif., fought for better wages.

But their efforts to start unions mostly fizzled. So last year, union backers tried something new: a ballot measure.

Voters swiftly gave them what years of picket lines and union-card drives had failed to secure — a $13-per-hour minimum wage for hundreds of Long Beach hotel workers.

A similar shift happened in San Jose, Calif., where voters in November awarded workers a higher minimum wage not just in hotels, but citywide.

The victories are on the cusp of an emerging trend: Ballot initiatives, labor experts say, have the potential to rewrite labor’s playbook for how to win concessions from management.

Long Beach and San Jose join a list of cities nationwide where voters, not unions, have won workers higher wages, demonstrating the power of this new labor tactic.

The trend has built slowly. Frustrated in their efforts to fight corporations for better pay and working conditions, labor unions began turning to city councils in the 1990s to pass so-called living-wage requirements.

The efforts were small at first, usually affecting only workers employed by government contractors. But as time wore on, scores of such measures passed, eventually totaling more than 140 nationwide. As the victories mounted, proponents have grown more ambitious.

In recent years, labor activists have begun bypassing city councils altogether and taking their push for higher pay directly to voters who, polls show, often view wage increases favorably.

Nationwide, the strategy is by no means a slam-dunk — ballot campaigns are pricey and, thanks to ballot requirements, nearly impossible to win in some states — but in California, where a well-organized signature drive can land almost anything on the ballot, it has almost always been victorious.

Some of the more recent ballot campaigns have been aimed at particular industries or business sectors, such as tourism.

But a few, especially far-reaching wage measures, have been crafted to apply to jobs of every kind and are imposed citywide. Five of these have been passed nationally, three through popular vote, resulting in minimum wages higher than federal requirements for whole cities.

San Jose’s measure was the most recent and passed with more than 59 percent of the vote. Every low-wage worker in San Jose stands to benefit from the city’s new $10 minimum wage, and every business must comply, no exceptions.

For the unions that backed the measure, which went into effect Monday, its passage represents a sweeping victory they could never have hoped to achieve through traditional labor-organizing tactics.

Long Beach’s measure is more limited, affecting only workers at large hotels, but it has brought a sudden turnabout in what had been a long, bitter and unsuccessful organizing effort by unions.

“The quality of my life, for me and my family, improved immediately,” said Romeo Trinidad, a Filipino immigrant who has worked as a housekeeper at the Hilton in Long Beach for a dozen years.

With his salary bumped from $10.81 an hour to $13, Trinidad said he was now able to finance a three-week trip back to the Philippines to see his parents, whom he hasn’t seen since 2010.

“This trip is a bit of a celebration,” he said. “The campaign worked. We won.”

It’s easy to see why labor advocates like these ballot measures, said Ruth Milkman, a sociology professor at City University of New York who has studied the rise of ballot-box labor activism. “When you’re fighting the management, you’re doing it completely on their turf, and they control that turf,” she said. “But when it’s in the public square, you have an even playing field.”

But opponents decry the strategy as a trick play meant to disguise unionization efforts.

“The unions spent more than $250,000 to get this on the ballot since they’ve been unable to unionize these hotels,” said Randy Gordon, CEO of the Long Beach Chamber of Commerce. He called the city’s living-wage provision “the worst ballot measure in the history of Long Beach.”

Experts say ballot campaigns allow union leaders to stay behind the scenes. Instead of unions, a coalition of community advocates, students and workers become the face of ostensibly grass-roots campaigns.

In San Jose, college students collected the 40,000 signatures needed to get it on the ballot. In Long Beach, small-business owners handed out literature to customers, hotel workers canvassed neighborhoods and clergy called for “economic justice” from the pulpit.

But the strategy is expensive. And some experts doubt that, despite labor hopes, it will play as well in other states with stricter ballot-measure laws.

“I don’t think the Long Beach measure will start a massive wave of imitation,” said Stephanie Luce, a labor studies professor at the City University of New York. “There aren’t enough places where this is allowed.”

And in both San Jose and Long Beach, there are some signs that, even for the workers who benefit, long-term results may be mixed.

In Long Beach, some workers lost their jobs. Servers at Mezcal restaurant in San Jose will choose between working one less hour each day or one less day each week in order to absorb the cost of the wage increase, said Adolfo Gomez, who opened the 20-employee restaurant seven years ago.

“In the food service industry, tipped workers were making less in base pay, but all of my servers were making much more with tips,” Gomez said. “For them, losing an hour’s worth of tips is more costly than not having the extra $2 an hour in salary.”

The popular Mexican restaurant brings in more than a million dollars in sales each year and is marginally profitable. The estimated $100,000 cost of the new $10-an-hour minimum-wage law may push the business into the red, Gomez said.

Other businesses in the city are considering raising prices or relocating, said Scott Knies, executive director of the San Jose Downtown Association.

“If workers keep their job and hours aren’t reduced, they’re a lot better off. But that won’t be everyone,” said David Neumark, an economics professor at the University of California-Irvine. “There are winners and losers.”

Trinidad counts himself among the winners even though the Hilton cut his workday by one hour.

His family of four has been sharing a one-bedroom apartment. After returning from his vacation, he plans to start saving his extra earnings to move into a bigger place.