On Thanksgiving Day, 2008, shoppers began lining up outside the Wal-Mart in Valley Stream, Long Island, at 5:30 P.M., near a small, handwritten sign that read “Blitz Line Starts Here.” Like many other retailers holding “doorbuster” Black Friday sales, Wal-Mart was offering deep discounts on a limited number of TVs, iPods, DVD players, and other coveted products. Only two months earlier, the U.S. economy had nearly collapsed, and although the Christmas shopping season was looking dismal, there was still some dim hope that the nation might be able to shop its way out of disaster, as we were advised to do after 9/11.

By two in the morning, the line ran the length of the building, past Petland, turned at a wire fence, and stretched far into the bleak parking lot of the Green Acres Mall, a tundra of frosted tarmac. There were already more than a thousand people. Store managers had placed eight interlocking plastic barriers between the front of the line and the outer doors to the store, to create a buffer zone that would keep people from crowding around the entrance. But at three people began jumping the barriers. The store’s assistant manager, Mike Sicuranza, spoke to the manager, Steve Sooknanan, who had gone to a hotel to rest, and told him that customers had breached the buffer zone. Sicuranza sounded frightened. Sooknanan told him to call the police.

The Nassau County police arrived soon after the call, and, using bullhorns, ordered everyone to get back behind the barriers. The police were still there at four, when Sooknanan returned to the store. Shortly afterward, a Wal-Mart employee brought some family members inside the barriers, angering the crowd. About two hundred shoppers pushed into the buffer zone. Those in front were squeezed against two sliding glass outer doors that led into a glassed-in, high-ceilinged entrance vestibule that also held some vending machines. These had been pushed to the center of the space, to prevent people from crossing it diagonally and entering through the exit doors. As more people gathered, in anticipation of the store’s opening, at 5 A.M., the pressure on the doors built and they began to shake. “Push the doors in!” some chanted from the back.

Employees asked the police for help. According to a court filing, the police responded that dealing with this crowd was “not in their job description,” and they left. Of the two-man security force that Wal-Mart had hired for Blitz Day, only one had shown up, and he was inside the store. Shortly before five, the crowd had grown to about two thousand people. The store’s asset-protection manager, Sal D’Amico, advised Sooknanan not to open the doors, but Sooknanan overruled him. He instructed eight to ten of his largest employees, most of whom worked in the stockroom, to stand at the sides of the vestibule as the outer doors were opened, and be ready to help anyone who tripped or fell.

One of those men was Jdimytai Damour, who lived in Jamaica, Queens; his parents were Haitian immigrants. Damour was thirty-four, and beefy—at six feet five inches tall, he weighed around four hundred and eighty pounds. Friends called him Jdidread, because he wore his hair in dreadlocks. He had been working at Wal-Mart for about a week, as a temporary employee in the stockroom. Like the others in the vestibule, he had no training in security or crowd control. A co-worker had reportedly heard him say earlier, “I don’t want to be here.”

Just before five, the workers realized that a pregnant woman, Leana Lockley, a twenty-eight-year-old part-time college student from South Ozone Park, was being crushed against the glass on the outer doors. The managers slid them open just enough to pull Lockley inside the vestibule. The crowd surged forward, thinking that the store was opening. The workers shut the doors again and braced both sliding doors with their bodies to keep them from caving in, as Sooknanan initiated the festive countdown, a Wal-Mart Blitz Day tradition. Ten, nine, eight . . . At zero, the doors were opened again. There was a loud cracking sound as both sliding doors burst from their frame, and the crowd boiled in.

Dennis Fitch, one of the workers standing at the entrance, was blown backward, through the inner vestibule doors and into the store. Others managed to jump to safety atop the vending machines. Some attempted to form a human chain on the other side of the vestibule, to slow down the crowd rushing into the store. A crush soon developed inside the vestibule, but the people who were still outside, pushing forward, weren’t aware of it. Leana Lockley was carried through the vestibule and into the store by the surge, and she tripped over an older woman, who was on the ground. As she got to her knees, she later said, she saw Damour next to her. “I was screaming that I was pregnant, I am sure he heard that,” she told Newsday. “He was trying to block the people from pushing me down to the ground and trampling me. . . . It was a split second, and we had eye contact as we knew we were going to die.”

Co-workers later testified that Damour was hit by one of the two sliding glass doors. As he went down, the door fell on top of him, and people fell over it. Maybe he got up again to help Lockley, but that’s not clear in camera and cell-phone-video footage of the scene. He just vanishes into the frantic tangle of limbs.

Lockley’s husband, Shawn, was able to pull her out, badly bruised. A healthy girl was born the following April. But though “Big guy down” was broadcast over the walkie-talkies that some of Damour’s co-workers carried, they had to fight their way through the crowd to reach him, and when they got there Damour’s tongue was out and his eyes had rolled back. The cops arrived at 5:05 A.M., and performed CPR (a cell-phone video made its way to YouTube), without success. Damour was pronounced dead at the Franklin Hospital Medical Center, in Valley Stream, at 6:03 A.M. The coroner’s report did not mention any bruises, fractures, or internal injuries, as it would have if he’d been trampled to death; the cause of death was listed as asphyxia.

Crowds are a condition of urban life. On subways and sidewalks, in elevators and stores, we pass in and out of them in the course of a day, without pausing to consider by what mechanisms our brains guide us through so easily, rarely touching so much as a stranger’s shoulder. Crowds are often viewed as a necessary inconvenience of city living, but there are occasions when we gladly join them, pressing together at raves and rock concerts, at sporting events, victory parades, and big sales. Elias Canetti, in his 1960 book “Crowds and Power,” sees these times of physical communion with strangers as essential to transcending the fear of being touched. “The more fiercely people press together,” he writes, “the more certain they feel that they do not fear each other.” In fact, a crowd is most dangerous when density is greatest. The transition from fraternal smooshing to suffocating pressure—a “crowd crush”—often occurs almost imperceptibly; one doesn’t realize what’s happening until it’s too late to escape. Something interrupts the flow of pedestrians—a blocked exit, say, while an escalator continues to feed people into a closed-off space. Or a storm that causes everyone to start running for shelter at the same time. (In Belarus, in 1999, fifty-two people died when a crowd tried to enter an underground railway station to keep dry.) At a certain point, you feel pressure on all sides of your body, and realize that you can’t raise your arms. You are pulled off your feet, and welded into a block of people. The crowd force squeezes the air out of your lungs, and you struggle to take another breath.