AS THE FOCUS shifted to Louisiana during the roll-call portion of last night’s Democratic National Convention, viewers could spot a young boy standing at stage right holding a sign showing a pair of aviator sunglasses—shorthand for Joe Biden. Metal-rimmed aviators have been a sartorial signature of the Democratic presidential candidate since well before that young boy was even born. The 77-year-old former vice president told the Skimm newsletter in 2016 that he’s been sporting aviators since he “was a freshman in college as a lifeguard.” Today, his Twitter bio reads, in part, “Loves ice cream, aviators & @Amtrak.”

Ray-Bans have long been Mr. Biden’s aviator of choice. In April, 2014, when he started an official Instagram account as vice president, his first post showed a close-up of his glittering gold sunglasses, with the “Ray-Ban” logo conspicuously at the center of the frame. In more recent images of the candidate, that logo can easily be spotted on the upper right of his shades and a representative for the Biden campaign confirmed that the candidate continues to sport Ray-Bans today. Starting at a relatively affordable $154, Ray-Ban’s aviators can be snatched up at just about any mall or department store across America.

Bausch Lomb, based in Rochester, N.Y., launched the design itself—large teardrop lenses suspended in a nimble wireframe—in 1937. Since then, the enduringly popular model, increasingly associated with Ray-Ban, has had an outsized pop-cultural impact, surfacing on actors in films like “Top Gun,” “Eat, Pray, Love” and “The Hangover.” Supporters of American manufacturing might be disappointed to know that in 1999 Ray-Ban was sold to Luxottica Group, a mammoth Italian eyewear conglomerate. (Ray-Ban declined to comment.)

Jordan Silver, the owner of Silver Lining Opticians in New York, said that prominent, ample sunglasses like the aviator “feel like a choice for someone with a lot of confidence.” He noted that a frame with larger lenses also often appeals to wearers around Mr. Biden’s age. Such customers “want the frame to hit a certain way to conceal” signs of age like wrinkles and under-eye bags. To date, Mr. Silver hasn’t had any customers cite Mr. Biden by name when asking for aviators, though it wouldn’t surprise him if they start to soon.

The Biden team and his supporters have turned the glasses into an avatar for their candidate. On Instagram, users can try out a “Team Joe Aviators” filter that virtually plants Mr. Biden’s sloping aviators onto their faces. His website sells a heather-gray T-shirt printed with red, white and blue sunglasses. Yet, unlike Donald Trump’s campaign, which energetically markets firetruck-red “Make America Great Again” hats, Mr. Biden’s platform does not officially sell any sunglasses yet, despite much Twitter chatter calling for such a move—or its fundraising potential.