Starbucks cafe in Mesa, Arizona votes to unionize, dealing a blow to the coffee chain

Starbucks was dealt a blow when workers at a location in Mesa, Arizona, voted to form a union.

Workers United, a branch of the Service Employees International Union, is the union that employees at the cafe voted to unionize under.

It is the first Starbucks location outside of the Buffalo, New York, area to vote in favor of unionizing.

Over the last six months, more than 100 Starbucks locations have filed for union elections, doubling their count in the last month after victories in Buffalo. The restaurant industry could see its historically low unionization rate rise as a result of those cafes.

A second store in Mesa has filed for a union election. The ballots from the NLRB have to be received by March 18.

Michelle Eisen, a barista at the Buffalo, NY, Elmwood Starbucks location, the first Starbuck location to unionize, helps out the local Starbucks Workers United, employees of a local Starbucks, as they gather at a local union hall to cast votes to unionize or not, Wednesday, Feb. 16, 2022, in Mesa, Ariz.

The regional director of the National Labor Relations Board will have to certify the ballots, which could take up to a week. The union will have to negotiate a contract with Starbucks. The employer and union don't have to reach a collective bargaining agreement. Workers who lose faith in the union can petition to decertify after a year, putting negotiations in danger.

After Starbucks workers at its New York location won the first union for employees of a company-owned location, Starbucks North American head Rossann Williams wrote a letter to all U.S. baristas, saying the company would bargain.

Liz Alanna, a shift supervisor at the Mesa store, said in a statement that they are excited and hopeful to start the bargaining process with Starbucks.

Starbucks did not respond to CNBC's request for comment.

Andy Barish wrote in a Thursday note to clients that unionizing doesn't appear to be a major financial risk to Starbucks in terms of large hourly wage increases or benefit demands. He said that the chain could suffer damage if it was mishandled poorly.

Starbucks has been accused of union busting by Starbucks Workers United. The company denied the claims. Executives were sent to Buffalo and Mesa stores in opposition to the union effort.

It is hard to imagine this issue turning into a maelstrom of negative PR for the stock, which has been weak recently.

Starbucks's market value has fallen to $106 billion, as its shares have fallen over the last year.

Starbucks has appealed to the National Labor Relations Board, which has caused a delay in the vote count. The vote tally in Mesa was also delayed. Workers were supposed to hear the result on Feb. 16.