For union organizers across Amazon's (AMZN  ) sprawling semi-automated facilities, Christmas came Dec. 23.

Last Wednesday, Amazon ratified its largest-ever settlement with the National Labor Relations Board over allegations that it had interfered with unionizing efforts at its Chicago and Staten Island facilities.

Employees there had been prohibited from being on company grounds either 15 minutes before or after their shift, limiting their ability to organize.

Under the deal, Amazon will undo that policy and notify workers both past and present of their rights to use its facilities to organize their unionizing efforts.

The agreement covers the more than 750,000 odd employees who power Amazon's U.S. operations, making it one of the largest settlements in the NLRB's history, said the regulator.

"This settlement agreement provides a crucial commitment from Amazon to millions of its workers across the United States that it will not interfere with their right to act collectively to improve their workplace by forming a union or taking other collective action," Jennifer Abruzzo, the new general counsel under President Joe Biden, said in a statement.

Amazon made no comment. In the past, the e-retailer said that it recognized workers' rights to organize but that they would be better served without a union.

This year, unionization drives have buffeted the firm at its Staten Island and Alabama facilities, efforts formally backed by the International Brotherhood of Teamsters.

Meanwhile, the pandemic-fueled surge in online shopping has spurred a massive hiring drive at Amazon, which now counts itself as the nation's second-largest employer.

At the same time, the high turnover, highly automated model Amazon once used to run its facilities has been strained by a phenomenon known as the "Great Resignation," where a record number of workers are now leaving their jobs in search of better working conditions or an improved lifestyle.

In response, Amazon has bolstered efforts to boost pay and improve the situation for its workers on the ground. In June, the company tweaked a once infamous policy that limited employee bathroom breaks. Meanwhile, this quarter alone, Amazon has pledged some $4 billion to help deal with the labor shortage.

However, these higher labor costs and a cooling appetite for online goods are now straining margins a the company, which posted its slowest sales growth in seven years last month.

Meanwhile, Amazon further has to contend with a decisively pro-union Biden administration and increasingly skeptical NLRB. Last month, the regulator threw out the results of a highly publicized, albeit failed, bid to unionize workers at Amazon's Alabama facility.

In that vote, more than 70% of employees voted against unionizing. But, despite that decisive margin, the NLRB alleges that Amazon interfered with the process by installing a mailbox outside of its facility.

No date has been set for that second election. Regardless, "the history of unions is always about falling forward," Janice Fine, a professor of labor studies at Rutgers, told the New York Times. "Workers trying, workers losing, workers trying again."