In a first for the Amazon's US facilities, warehouse workers in Staten Island, New York, have voted in favor of joining a union.

The union's win, if certified by the federal labor board, adds momentum an organizing movement that's been gaining steam around the country.

The tally of of 2,654 yes votes to 2,131 no votes came after six days of in-person voting at the warehouse and an intense campaign.

In the lead up to the vote, the union filed complaints to the National Labor Relations Board alleging that Amazon engaged in unfair labor practices.

The Amazon Labor Union, a new group that was formed by current and former Amazon workers, emerged from workers' efforts to demand better COVID-19 protections in 2020.

The group eventually began an organizing bid after some workers involved in planning walkouts were disciplined or fired.

That included worker Chris Smalls, who went on to become the face of the organizing movement after his firing.

Separately, a vote on unionization at an Amazon facility in Alabama failed on Thursday, though the result could be affected when hundreds of challenged ballots are resolved.

The Staten Island victory defied predictions of labor experts, who noted before the election that the union only secured support from 30% of workers when they formally requested a union election.

Amazon expressed skepticism that the workers' group had even achieved that benchmark but agreed to move ahead with the election.