Starbucks Barista Gianna Reeve, part of the organizing committee in Buffalo, New York, speaks in support of workers at Seattle Starbucks locations that announced plans to unionize, during a rally at Cal Anderson Park in Seattle, Washington on January 25, 2022.Starbucks Barista Gianna Reeve, part of the organizing committee in Buffalo, New York, speaks in support of workers at Seattle Starbucks locations that announced plans to unionize, during a rally at Cal Anderson Park in Seattle, Washington on January 25, 2022.

Starbucks baristas in Seattle voted to unionize on Tuesday, making them the first in the company's hometown to do so.

Starbucks cafes in Buffalo, New York, and Mesa, Arizona, have decided to form a union with the help of the Service Employees International Union. Only one Starbucks location in the Buffalo area has voted against unionizing.

The growing union push is one of the challenges that incoming interim CEO Howard Shultz will face once he returns to the helm of the company he helped grow into a global coffee giant. Kevin Johnson can retire and the board can search for a long-term replacement when Schultz takes over on April 4.

Starbucks gained a reputation as a generous and progressive employer, a position that is now in jeopardy as the union gains traction and workers share their grievances.

Nine workers voted to unionize at the Broadway and Denny Way location. One ballot was not counted because it was challenged. The company's flagship Reserve Roastery, a flashy cafe designed to compete with more upscale coffee shops, is one of six Starbucks locations that have filed for union elections.

The union has galvanized other locations nationwide after the initial Buffalo victories. More than 150 Starbucks cafes have filed for union elections with the National Labor Relations Board in the last six months.

Only a small portion of the company's footprint has been swept up in the union push. Starbucks has nearly 9000 locations in the U.S.

The regional director of the National Labor Relations Board will have to certify the Seattle ballots, which could take up to a week. The union will have to negotiate a contract with Starbucks. Labor laws don't require that the employer and union reach a collective bargaining agreement, and contract discussions can drag on for years.

The chair of the annual shareholders meeting at Starbucks said the company understands and recognizes its workers' right to organize.

She said that they are negotiating in good faith and want a constructive relationship with the union.

She said on CNBC that Starbucks made some mistakes when asked about the union push.

When you think about it, we think Howard is capable of engaging with our people in a way that will connect with them.

It's possible that his return to the company and his approach to the organizing push was signaled by his appearance in Buffalo ahead of the union elections.