And, as it turned out, bumpers were also a boon to advertisers for national parks, motels, and other tourist attractions. Capitalizing on the wanderlust of war-weary Americans who’d scrimped and saved and were now eager to drive their new automobiles, marketers would often affix bumper stickers on tourists’ cars while they were visiting the attraction, explains Mark Gilman, the chairman of the board at Gill-Line. They were often a point of pride for consumers: “It meant that you’d been somewhere,” he says.

By 1950, Gill had built a significant business selling stickers and similar products in the specialty advertising industry. The company’s first large volume request was 25,000 bumper stickers for Marine Gardens, a tourist attraction in Clearwater, Florida. But by the next decade, mass orders often skewed political: In 1968, the company printed 20 million stickers for the presidential campaign of the notorious segregationist Alabama governor George Wallace. (It has also printed stickers for candidates including LBJ, Kennedy, and Reagan.)

If you look closely at a bumper sticker, you’ll likely see a label indicating which union printed it—my Bernie Sanders sticker, for example, was made by Sign Display Local 100. For this reason, Gilman says, bumper stickers are often popular with Democratic candidates. “We’re making a lot of Bernie Sanders bumper stickers this year,” he tells me.

The company has sold more than $2 million in bumper stickers this year, Gilman says, but sales of bumper stickers have been dropping. He blames it on digital and social-media advertising as replacements for the stickers, buttons, and campaign pins of yore.

Larry Bird, a curator at the Smithsonian’s National Museum of American History, agrees that social media has played a role in the decline of bumper stickers. For Bird—a specialist in American political history and symbols—bumper stickers represent the last vestiges of the old “hurrah” campaigns of the 1950s, which were characterized by parades, painted tractor trailers, and rallies where campaigners would distribute their wares. Today, campaigning is significantly more manicured for television, and has lost what Bird calls the “thingness” that comes with receiving a button or bumper sticker from your favorite candidate.

The premise of bumper stickers, he says, is “actual physical contact and connection through that thing. In other words, I’m giving you this thing with my name on it, and I’m looking at you and you’re looking at me, we’re interacting.” It’s a more tangible declaration than a Facebook post: Postwar tourist stickers said, “I went somewhere”; political bumper stickers say, “I care about something.”

A nice idea, but bumper stickers and the people who sport them are now often seen in a negative light. Kim Kardashian, when asked by talk show host Wendy Williams if she had tattoos, famously offered this wisdom: “Honey, would you put a bumper sticker on a Bentley?” And a 2008 study by Colorado State University researchers found that people who put bumper stickers on their cars tend to be more aggressive, territorial drivers.