Every four years, the Smithsonian dispatches a small expedition to the Republican and Democratic National Conventions, to collect artifacts for the National Museum of American History. Their finds—a mixture of objects both homemade and mass-produced, profane and devotional—are sent to Washington, where the best join a trove of a hundred and thirty thousand political relics, including, for example, Abraham Lincoln’s top hat.

One afternoon, less than two weeks after the Conventions had ended, the museum permitted a visitor to enter the archives of the Division of Political History—a windowless industrial space, with pipes overhead—on the condition that its precise location within the facility remain unpublished, to avoid tempting thieves. The new artifacts were still being bagged in acid-free plastic and tagged with field notes. They were temporarily arrayed—Democratic material on one side, Republican on the other—on a long chest of drawers, which contained objects from previous episodes of American history: “Goldwater Billboards,” “World War I Posters: Uncle Sam/Women/Ethnic.”

The 2016 expedition team consisted of two curators, who set out for the Conventions carrying large black portfolio cases. One of them, Jon Grinspan, noted, “The portfolio kind of says, ‘We’re not crazy people.’ ” Some of the more interesting objects have to be extracted delicately. “There’s a little element of trying to tell people that you’re not stealing their stuff,” Grinspan said. Come on too strong, and people get spooked. “They’re proud of their hat. They’re proud of their poster. And the last thing you want to do is surround them.”

His colleague, Lisa Kathleen Graddy, an expert on the woman-suffrage movement, has learned to identify her targets early. “You soften them up on Day One,” she said. Regardless of the fate of their candidate, donating to the Smithsonian can give Convention-goers a feeling of victory. “I asked a Bernie Sanders delegate from Florida for her hat, and she started to cry,” Graddy recalled. “The idea that we weren’t pushing him aside from history, that the Smithsonian was going to say, ‘Bernie Sanders happened,’ was incredibly important to her.”

Grinspan asked, “Was that the woman with the picture of her kids on the hat?”

Graddy shook her head. “It was the one with the bird coming out of the top.”

Once an object comes through the Smithsonian’s door, it becomes a specimen, to be handled with white cotton gloves: iPhone cases, a whoopee cushion, emery boards, bottle openers, plastic signs, and dozens and dozens of lapel buttons. Grinspan identified a “Black Girls Vote” button as “very 2016,” because, he said, “since 2008, African-American women have had the highest voter turnout of any demographic group.” There were niche products—a button with Trump’s name in Hebrew and the message “He’s not just our candidate. He’s mishpocha! ”—and items that had not been allowed into the arenas, such as a sign that read, “America Was NEVER Great! We Need to OVERTHROW This System.”

Harry Rubenstein, the curator who heads the division, sat beside the loot. “In a sense, it’s just meaningless swag,” he said. “In another sense, these are the tools of democracy. There is a series of questions that the founding generation faced, that we still face: Who gets to participate? How do you actually get these people to participate? How do you inspire people?”

Over the years, the curators have learned that some delegations make for lousy scavenging. Oregonians pack out their garbage, like good campers. New Yorkers sometimes cut deals with the local historical society. The job can be unsavory. After a night of booing, a Sanders supporter peeled off a damp Day-Glo green T-shirt (it bore the message “Enough Is Enough”) and donated it to Graddy. “It lay on the floor of my hotel room overnight to dry out,” she said. What can’t be captured on-site must be obtained later. “We got a lovely e-mail from my cape lady,” Graddy told her colleagues. She’d been working on a Democrat with a carefully stitched Hillary Clinton superhero cape.

Grinspan saw a potential connection. “We have women’s-suffrage capes going back to when?”

“Yeah,” Graddy said. “I want to display it with a cloak from the 1913 parade down Pennsylvania Avenue.” Some of the best items will be exhibited next summer, in a show titled “American Democracy: A Great Leap of Faith.”

For Grinspan, aspects of the 2016 campaigns make more sense when viewed through the wide lens of history. He said, “A hundred and fifty years ago this summer, Andrew Johnson toured the country, comparing himself to Jesus and screaming at crowds. He seemed like a megalomaniac.” The Republic survived. But perhaps history should not be so reassuring. “It can almost be an opiate,” Grinspan said. “You can say, ‘Well, we had a civil war in this country. This is nothing.’ ” ♦