The campaign to unionize Starbucks stores has made headway in the coffee chain's hometown, with the union winning an election at a store in Seattle on Tuesday.

Workers at a store in Seattle's Capitol Hill voted unanimously to join the union Workers United, which has been organizing baristas around the country since last year. The union Starbucks stores in New York and Arizona have been boosted by the 9-0 election victory.

More than 140 stores in 27 states have filed petitions for union elections, and it is likely that their ranks will grow in the coming weeks. Out of eight elections, the union has only lost one.

Rachel Ybarra, a barista at the Seattle shop, said after the vote count that a resounding victory in the company's backyard could embolden workers elsewhere to try to form a union.

Ybarra said that this will make other stores more confident in contacting them.

A Starbucks spokesman said in an email that they still believe in Starbucks and will respect the legal process.

The Starbucks Workers United campaign began in the Buffalo area of New York. 13 workers will be part of the bargaining unit at the Seattle store.

“I know this is going to make other stores more confident to contact us.”

- Rachel Ybarra, Starbucks barista in Seattle

Until last year, all of Starbucks' company-owned stores in the US were non-union. The company has opposed the union campaign, with managers holding meetings with workers urging them to vote no.

The National Labor Relations Board, which referees collective bargaining in the private sector, found merit in the union's claims that Starbucks discriminated against two pro-union workers. Starbucks denied the allegations.

Last week, Starbucks announced that Howard Shultz would be returning as the company's leader. At a critical juncture in the unionization effort, Schultz will take over.

He told Starbucks employees in a message last week that they need to take a hard look at how they are doing.

Starbucks has dealt with unions before. Several of the chain's original stores and its roastery in the Seattle area were represented by a union in the 1980s. The union was decertified and no longer represented those workers by the early 1990s, a development that was approved in a memoir by the author.

The Industrial Workers of the World began an organizing effort in the early 2000s, but the company later succeeded in repelling them.

The current campaign has already racked up a string of victories, and baristas promise more to come.

If he hopes to slow the organizing campaign, he will be fighting a losing battle, warned a worker at the newly unionized Seattle store.

He will find a whole new reality if he comes in expecting his old tactics to work.