Starbucks baristas' fast-growing unfair labor practice strike is expected to hit historic levels Tuesday as hundreds of stores nationwide prepare to join walkouts at the coffee giant.The Starbucks Workers United strike,

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

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.