STARBUCKS workers in Chicago have become the latest to join the unionisation drive at the global coffee chain’s stores across the US.

The workers penned letter to CEO Kevin Johnson saying that staff at the Logan Square store could only have a true partnership and voice at work by forming a union to negotiate their terms and conditions and “secure appropriate wages.”

In the letter, workers expressed their love for their job and highlighted the “unwavering support” from their manager to transform the culture of their store.

The union would bring “a democratic voice to partners” — the corporate name used by Starbucks for its workforce — workers said, adding that it was “a crucial moment for Starbucks to do the right thing.”

The company has been reluctant to recognise unions, describing them as “a barrier” in the workplace. 

It has run a hostile campaign of intimidation to stop staff organising collectively, spending millions on a union-busting company.

But workers at the Elmwood store in Buffalo, New York, became the first in Starbucks’s 50-year history to unionise last month following a historic vote ratified by the National Labour Relations Board NLRB.

The Chicago campaign has the backing of Congressman Chuy Garcia who offered his support to the workers in his district.

“I stand by you and will be stopping by soon to stand with you in solidarity,” he tweeted on Saturday.

It is the latest store to join the growing unionisation campaign across the US. 

Employees in cities including Boston, Knoxville, Tennessee, and Starbucks’s hometown of Seattle have filed petitions with the NLRB.

On Friday the board granted a request by Arizona workers to hold a store-by-store vote, rejecting the company’s arguments against the process.