It’s half an hour before sunrise and I’m walking around Manhattan’s Chinatown with Robin Nagle, who teaches anthropology at New York University. “Look, there!” Nagle shouts as if she’d spotted a bird, which at that hour had only recently begun to chirp. The city is as still as it’ll ever be, so the massive white garbage truck clanging its way down a side street stands out.

Nagle studies trash, and not just from behind a desk. As part of her research Nagle actually got a job as a sanitation worker for a time, getting up at 5 a.m. to drive trucks, haul trash, and plow snow, then dash back to campus to teach evening classes. She’s now the “anthropologist in residence” at New York City's Department of Sanitation. Her book, Picking Up, is the culmination of years spent researching waste management, both in archives and on the street.

When we get to the truck, Nagle and two workers immediately launch into shoptalk. One of them starts listing some of the vehicle’s improved specs: air ride seats (no more concussive shocks), air conditioning (nonexistent just three years ago). “We always get the new trucks,” he says, gesturing to his partner, “because they know he takes good care of them. I like working with him. I’m not gonna get killed.”

Nagle makes a point of reminding people how dangerous trash collection is. Sanitation workers in New York die more frequently than police officers or firefighters, a fact that surprises even sanitation workers partly because their deaths rarely get the same news coverage. They get hit by cars, poisoned by toxic chemicals, cut by rusty metal, and hit by objects that occasionally shoot out of the compactor in the back of their trucks. Nagle heard of one guy who got slammed in the stomach by a bowling ball that came rocketing out the back of the truck. And that’s to say nothing of the everyday unpleasantness. Spring is the only season that sanitation workers call by its own name—summer is “maggots,” autumn is “leaves,” and winter is “night plow.” It’s one of the most dangerous jobs in the country, and Nagle feels it doesn’t get nearly the respect it deserves.

“I wrote the book, Picking Up, about your job and how important it is,” she tells the duo. “In fact, I wrote that it’s the most important job on the street. Not to take away from police and fire, but if we’re not here first there’s no city.”

The history of the sanitation department in New York is the story of the city running up against a limit to its growth, and grudgingly figuring out what to do with its trash. The first laws about throwing away garbage were developed only after cholera and yellow fever were full-blown epidemics; dumping grounds were moved out of the harbor only after ships started running aground on undersea mountains of refuse. A third of lower Manhattan is built on fill, much of it chucked into the river by early New Yorkers.

It took a Civil War colonel named George E. Waring Jr. to clear the streets of shin-deep drifts of offal, and he did it by turning the department into a quasi-military organization, with rigid chains of command, regular patrols, bright white uniforms, and even, in 1896, a martial-style parade with garbage men marching in ranks and twirling brooms. “He recognized it as a perpetual war,” says Nagle.

The uniforms didn’t just instill discipline, they also made people notice the garbage men. Nagle was driven to study trash collection partly because our culture seems so determined to ignore it. Early in Picking Up, Nagle describes a trash collector ogling a woman on the street and makes the point that he can do this because he’s practically invisible—he’s part of the city’s background machinery, and a part we’d rather not think about.

For such an important and universal activity, she’s found the practice of waste management to be strangely ignored even in academia. Her attempts to find the roots of sanitation slang came up empty. She’s working to archive the history of the city’s waste management, and is trying to found a new discipline called Discard Studies.

One of her assignments for her students forces them to hold on to everything they would normally throw out—all their shopping bags, plastic forks, tissues, and to-go containers—for 48 hours. “You learn a lot about how deeply ingrained the habit of letting go and throwing out is,” says Nagle. “All of my students will say that at some point they forgot and threw something out.” Part of the reason we’re able to cram so much into a single day—to maintain what Nagle calls “our average necessary quotidian velocity”—is that we can drop anything we don’t need. I bought, drank, and tossed two cups of coffee while walking around with Nagle.

She’s also working to create a museum of sanitation, along the lines of New York’s Transit Museum. Initially, people seemed enthusiastic, but then she ran into the eternal problem of waste management: NIMBY. Not in my back yard—even when it’s just a museum about garbage collection, people still don’t want it next door. “Siting it will be a problem, which is fascinating to me. When I say museum, people say, Oh, yes! But then I say sanitation museum and they say, Oh, no!” Nagle says. “I’ll have to be careful about how I pitch it.”