Drivers in Massachusetts won the right to unionize in a statewide ballot initiative on Wednesday, a first-of-its-kind victory that could set a precedent for gig worker legislation across the country.

The initiative went from 54 percent to 46 percent and gives drivers for apps like Uber and Lyft the ability to form unions that have collective bargaining power — while still being classified as independent contractors.

The ballot measure was controversial among labor advocates, many of whom opposed it as a setback in the larger movement to reclassify rideshare drivers as employees who would be routinely protected by the National Labor Relations Act.

The initiative, brought by the Service Employees International Union and the International Association of Machinists and Aerospace Workers, will create a hearing process for drivers to take complaints of unfair labor practices to a state board. But it contains no language about strike protection.

“Rhetorically speaking, it’s a win,” said Katie Wells, a senior fellow at Groundwork Collaborative, a progressive nonprofit. “But is it a material victory that will actually change the power inequality and the ability of these workers to survive an exploitative and predatory economy? Probably not.”

This practice is known as industry bargaining, where workers band together as an industry, in this case as drivers, and not as employees for a specific company. The measure does not include protection for drivers who deliver food.

A national wave of legislation on the gig economy includes Proposition 22 in California and minimum wage and benefits laws in New York, Washington state and Minnesota. In June, Uber and Lyft settled a yearslong legal dispute with the Massachusetts attorney general and agreed to pay their drivers in the state a minimum rate with some benefits.

In an interview, April Verrett, president of the SEIU, called the result “a monumental step forward” for gig workers who have been written out of labor laws.

Uber and Lyft were not opposed to the initiative.

But Uber said in a statement that it was telling that the ballot proposal “simply squeaked by” in a state known for its strong support of unions. “It is clear that voters have concerns, and it is now up to the Legislature to address their concerns,” the company said.

Statewide labor laws could provide protections for workers that close loopholes in federal laws, which are already particularly weak for gig workers, said Sharon Block, a labor professor at Harvard Law School. “So it will be a very exciting experiment to see some kind of tailor-made model for collective bargaining,” she added.

But that model can be tricky and, if applied incorrectly, deter workers from fighting for additional rights such as employee classification, says Veena Dubal, a professor at the University of California, Irvine, School of Law.

“The idea is that if there are bargaining laws at the state level for National Labor Relations Act employees, you want those laws to be written very carefully and take into account the shortcomings of federal law,” Ms. Dubal said. “This is not that law, which is why Uber and Lyft are not opposed to it.”

Drivers with Massachusetts Drivers United, which represents 1,800 drivers across the state, were largely split on the measure, said Kelly Cobb-Lemire, an organizer with the group.

“We are not against unionization,” Ms. Cobb-Lemire said. “But we believe this does not go far enough.”