Starbucks workers around the U.S. have begun a three-day strike.

The walkouts are part of their effort to unionize the coffee chain’s stores.

Starbucks Workers United says more than 1,000 baristas at 100 stores are planning to walk out.

The strike will be the longest in the year-old unionization campaign.

More than 264 of Starbucks’ 9,000 company-run U.S. stores have voted to unionize since late last year.

Bargaining has begun but Starbucks hasn’t reached a contract agreement with the union at any store. Starbucks opposes the unionization effort.

The company said Friday that the strikes were having a limited impact and most stores remained open.