Workers at some Starbucks stores started a five-day strike Friday in three U.S. cities, including Chicago, to protest lack of progress in contract negotiations with the company. S

Workers at more than a dozen Chicago area Starbucks were on strike Christmas Eve, union organizers said, as baristas escalated a national walkout that began in three cities, including Chicago, on Friday.

The walkouts in Los Angeles, Chicago and Seattle come after talks between the company and the workers’ union failed to produce an agreement on raises.