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

Across the country, baristas at more than 300 cafes were striking, according to their union, Starbucks Workers United.

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

Workers in about 10 to 15 stores across the Los Angeles, Seattle and Chicago areas kicked off the strike, which spread to a similar number of stores in three additional metropolitan areas each day. By Monday, baristas in more than 50 stores in cities like Boston, Dallas, Denver, New York and Philadelphia did not report for work.

Starbucks baristas went on strike at several stores in Chicago, Seattle and Los Angeles on Friday, with their union warning the walkouts could spread to hundreds of cafes by Christmas Eve if the coffee giant does not meet workers’ demands at the bargaining table.

Starbucks workers' strike expands to over 300 stores

If a strike by Starbucks Corp. (NASDAQ: SBUX) workers is supposed to get them better benefits and treatment, the store count affected by the union action is modest. About 300 of Starbucks’ 16,621 U.S.