SEATTLE — Amazon will face its first union vote on U.S. soil in seven years on Feb. 8, when ballots will be mailed to warehouse workers in Bessemer, Ala., for an election that could emerge as a major labor battle at one of the country’s largest employers.

A National Labor Relations Board hearing officer ruled Friday that roughly 6,000 workers at the facility will have seven weeks to cast their ballots to be represented by the Retail, Wholesale and Department Store Union. The decision granted the union’s request to hold the balloting entirely by mail, over the objections of Amazon, which wanted in-person voting.

The vote alone is a massive turn at a company that has long opposed the unionization of its U.S. workforce. Now, Amazon and the union will likely engage in a pitched battle to win over the workforce at a warehouse that opened only last spring.

(Amazon founder and chief executive Jeff Bezos owns The Washington Post.)

Moreover, the election itself is one of the largest labor fights among private U.S. employers in recent history. Union votes more typically cover dozens, if not hundreds, of workers. One of the largest elections in recent years was a successful drive by teaching and research assistants at Harvard University to join the United Auto Workers two years ago. About 3,500 workers voted in an election in which more than 5,000 students were eligible.

The RWDSU, which filed in November a petition with the NLRB to hold the Amazon unionization vote, will need to win a majority of votes cast in the balloting, not a majority of the bargaining unit itself. The board also ruled that all employees in union-eligible jobs who have worked an average of four hours or more a week during the 13 weeks preceding the election can cast ballots.

Holding the vote in person, for which Amazon advocated, would have required the board to send staff into a region where the spread of the novel coronavirus is particularly high. Moreover, in-person voting could have disenfranchised voters that have covid-19 or are concerned about contracting the disease, wrote Lisa Henderson, the acting regional director of the board’s Atlanta office, in her decision.

Mail-in balloting “will protect the health and safety of voters, Agency personnel, the parties’ representatives, and the public during the current health crisis,” Henderson ruled.

The ballots need to be received by March 29, and the board will begin counting the next day. Amazon and the union will be able to monitor the count via video conference.

The union tweeted congratulations to workers about achieving a vote.

Amazon continued to contend that in-person voting would make it “easy for associates to verify and cast their vote,” spokeswoman Heather Knox said in an emailed statement. The company “will continue to insist on measures for a fair election, and we want everyone to vote, so our focus is ensuring that’s possible.”

Knox previously said the union doesn’t represent “the majority of our employees’ views.”

Both Amazon and the union are likely to work hard to win over workers during the seven-week voting period. Amazon has retained Morgan Lewis & Bockius, seen as one of the top anti-union law firms in the country. Amazon used Morgan Lewis when it successfully fought off a union representation bid by a small group of equipment maintenance and repair technicians at its Middletown, Del., warehouse in 2014.

Already, Amazon has set up an anti-union website — DoItWithoutDues.com — discouraging workers from paying dues and joining the RWDSU.

“There’s so much MORE you can do for your career and your family without paying dues,” the site reads.

Amazon’s Knox called the site “educational," adding that a union “will impact everyone at the site and it’s important associates understand what that means for them and their day-to-day life working at Amazon.”

A successful union drive in Bessemer would mark a major turning point for labor at Amazon, which employs more than 1.1 million workers worldwide. No unions represent its U.S. warehouse workforce, even as much of its European warehouse staffs are union members.

Amazon’s Bessemer workers are organizing as the company’s warehouse staff around the globe have voiced concerns about their safety during the coronavirus pandemic. In October, the company said nearly 20,000 of its U.S. employees had tested positive or had been presumed positive for the virus since the pandemic took hold. The company hasn’t publicly updated those figures since.

A website created by the union at the start of the organizing drive encouraged Bessemer warehouse workers to sign authorization cards to secure not just better pay but also improved safety.