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

Starbucks workers have expanded their strike to more cities and closed 59 stores across the U.S. as of Monday, the union said amid stalled negotiations.

The strike, which began Friday in Los Angeles, Chicago and Starbucks’ hometown of Seattle, continued spreading to stores across the country over the weekend.