Starbucks workers at union stores throughout the U.S. launched a three-day strike Friday. Dec. 16. in an effort to unionize more of the coffee chain’s locations.

More than 1,000 baristas at 100 stores planned to walk out, according to Starbucks Workers United, the labor group organizing the effort.

Four Southern California stores, including two in Los Angeles, one in Lakewood and another in Long Beach, participated in Friday’s walkout. The two Los Angeles locations and the Lakewood store shut down Friday and will remain closed through Sunday, while the Long Beach store was closed only on Friday.

The “Double Down Strike” will be the longest in the year-old unionization campaign and is the latest escalation against Starbucks’ campaign of anti-union bullying, union officials said.

Starbucks opposes the unionization effort, saying the company functions better when it works directly with employees.

But Starbucks Workers United said non-union employees have the right to negotiate a union contract and gain a voice in setting organization policies, workplace rights, health and safety conditions, protections from unfair firings or discipline, seniority rights, benefits and wages.

The union said it expected the walkout would shutter some stores entirely, while managers and workers at others might choose to keep operations going.

Workers on the picket line are letting customers know they can support organizing by baristas by not buying Starbucks gift cards this year, as part of the workers’ “NoContractNoGiftCards” campaign.

Misha Spencer, a barista at a Long Beach store at 3390 E. 7th St. said she’s committed to unionization.

“We are going to continuously show up until Starbucks comes to the bargaining table,” she said. “As someone who is passionate about coffee and lives in the community where they work, I believe Starbucks has a responsibility to make sure their baristas are taken care of, not just their CEOs and board members”

This is the second major strike in a month by Starbucks’ U.S. workers. On Nov. 17, workers at 110 Starbucks stores held a one-day walkout. That effort coincided with Starbucks’ annual Red Cup Day when the company gives reusable cups to customers who order a holiday drink.

At least 264 of Starbucks’ 9,000 company-run U.S. stores have voted to unionize since late last year.

In a statement issued Friday, Starbucks said Workers United “continues to spread misleading claims” while disrupting operations at stores.

“Despite these delay tactics, we remain focused on working together and engaging meaningfully and directly with the union to make Starbucks a company that works for everyone,” the company said.

Workers at non-union stores, who say they are overworked, underpaid and often working erratic schedules, are looking to have a stronger voice on the job.

“Our industry can be tough,” Starbucks Workers United says on its website. “We know what it’s like to be understaffed and overworked, on our feet for hours at a time, memorizing long menus, presenting a sunny demeanor to customers — even when they’re entitled, or impatient, or rude, or creepy.”

Tyler Keeling, a barista and lead union organizer at the Lakewood store, said Starbucks recently closed a Seattle location — the first of the stores to unionize a year ago — and has since shuttered eight other union stores, primarily in the Pacific Northwest.

“We are protesting the closing of those stores,” he said. “We also want the company to allow credit card tipping at union stores. They implemented that at all of the non-union locations, but not at the union stores.”

The two sides have begun contract talks in about 50 stores, but no agreements have been reached.

The process has been contentious. The National Labor Relations Board has issued more than 45 complaints encompassing more than 900 alleged violations of federal labor law, the union said.

Starbucks, meanwhile, has filed 47 charges against Starbucks Workers United, including allegations that it defied bargaining rules when it recorded sessions and posted the recordings online.

Starbucks said it has encouraged employees to participate in the collective bargaining process so that employee voices are heard.

“By the end of 2022, we will have appeared in person for more than 75 single-store bargaining sessions, and we continue to engage meaningfully and directly with the union,” the company said.

So far, the labor disputes haven’t appeared to dent Starbucks’ sales. Starbucks said in November that its revenue rose 3% to a record $8.41 billion in the July-September period.

Staff writers Kevin Smith and Brittany Murray and The Associated Press contributed to this report.