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.