It was 11 days before Christmas in 2018, and Amazon’s warehouse in Shakopee, Minnesota, was operating at full tilt. At the rear of the facility, waves of semi trucks backed up to a long row of loading docks, some disgorging crates of new merchandise and others filling up with outbound packages. Inside the warehouse, within dark, cyclone-fenced enclosures, thousands of shelf-toting robots performed a mute ballet, ferrying towers of merchandise from one place to another. And throughout the cavernous interior, yellow bins brimming with customers’ orders zipped along more than 10 miles of conveyor belts, which clattered with a thunderous din.

Negotiating all the distances and tasks that fall between those pieces of machinery were the people. Like most of the 110-plus US facilities that Amazon calls fulfillment centers, the warehouse known as MSP1—named for its proximity to the ­Minnea­po­­lis-Saint Paul airport—employs more than a thousand workers, including hordes of temps brought in for the holidays. They power-walked (running was forbidden) across roughly 850,000 square feet of polished concrete, following green-taped paths on what amounted to a giant game of Pac-Man the size of 14 football fields.

Additional reporting by Saraswati Rathod.

Among them was William Stolz, 24, a lanky Wisconsinite who’d been at Amazon for a year and a half. As a “picker,” his job was to hover at the dim perimeter of a cyclone fence and retrieve customers’ orders from the robot-borne storage pods that came to his station. He would stoop, squat, or climb a small ladder to grab items and then rush to place them in one of the yellow bins that sped off to the packaging department. There, another crew of workers boxed orders, reportedly at a rate of 230 per hour, sending them off in cardboard cartons bearing the trademarked Amazon smile logo. Stolz says he and his fellow pickers were expected to fetch more than 300 items every 60 minutes. And, according to workers, Amazon’s inventory-tracking system closely monitored whether they were hitting their marks.

The pace that Amazon demanded was inhumane, Stolz thought. Many of his coworkers endured pain from leg, back, and shoulder injuries as they strained to hit their hourly rate—which was one of the many reasons Stolz had decided to walk off the job that afternoon, December 14, at precisely 4 o’clock.

December 2019. Subscribe to WIRED. Photograph: Jessica Chou

Stolz and several coworkers had been planning the coordinated walkout for weeks, but now, as he counted down the minutes, he felt anxious and alone. “I was watching the clock at my station. You know, ‘3:57 … 3:58 …’” he recalls, “just getting really nervous.” His work station was relatively isolated, and he couldn’t see anyone else around him who planned to participate. He was momentarily gripped by the fear that he’d be the only one to go through with the plan.

Reminding himself that he’d made a commitment, Stolz summoned his courage; when the clock struck 4, he logged off his computer and headed for the stairwell. As he reached the ground floor, he felt a sense of relief. Trickling down the stairs after him he saw the familiar faces of other workers he’d been getting to know over the past several weeks as they had discussed what to do about conditions in the warehouse. Unlike him, most of his fellow strikers were Somali Muslim immigrants. Many of their faces were framed by hijabs.

Clocking out quietly, they walked through airport-style metal detectors, past private security guards. They stopped at their lockers to bundle up in heavy coats, gloves, and hats. “We gathered by the front doors for a few minutes,” Stolz recalls. “That way, if anybody was coming out late, they wouldn’t get scared.”