Former employees and supporters join unionized Starbucks employees as they carry signs in support of a strike in Virginia in 2023.SAUL LOEB/AFP via Getty ImagesStarbucks' largest workers' union announced that it would strike in three major cities on Friday.The Starbucks Workers United union said that stores in Los Angeles, Chicago, and Seattle would participate.The union said it was protesting Starbucks' unfair labor practices and low wages.Starbucks' largest workers union announced that it would go on strike in Los Angeles, Chicago, and Seattle, where it is headquartered, just days ahead of Christmas.On Wednesday, the union told BI that it would strike to protest hundreds of unresolved unfair labor practice cases and the company's failure to negotiate a sufficiently comprehensive pay package."Starbucks baristas are going on five days of escalating ULP strikes in response to the company backtracking on our promised path forward, starting tomorrow in Los Angeles, Chicago, and Seattle," Starbucks Workers United said in Thursday statements.It added that the strikes would soon be "coast-to-coast."In a statement to BI, the union said the strikes could reach "hundreds of stores" unless the company works to achieve collective bargaining agreements.The company has 11,161 self-operated stores and 7,263 licensed stores in North America.