When John F. Kennedy Jr.’s plane crashed on July 16, 1999, killing both Mr. Kennedy and his wife, Carolyn Bessette Kennedy (as well as Carolyn’s older sister), at the peak of their glamour and celebrity, the couple became not just another tragic story, but a symbol.

Think pieces proliferated about what it all meant: about the Kennedy curse and promises unfulfilled; about another chapter in, as The New York Times wrote in an editorial, the story of “unfinished journeys, of magnetic personalities cut down far too early.”

He founded George magazine; she had been a publicist at Calvin Klein. Together they embodied not only the next golden generation of a sprawling, mythic family, but also the apotheosis of the collision between fashion, pop culture, magazines and politics that defined New York in 1990s. Seemingly it was the last gasp of the monoculture, when discretion in both dress and demeanor was its own kind of currency and everyone agreed on who did it best.

Little wonder that as fascination with that era reaches a new pitch, Ms. Bessette Kennedy has emerged as the ghost influencer of the season — one who has particular resonance as stealth wealth evolves into an embrace of more functional minimalism in the face of global chaos; disillusionment grows with the cesspool that the digital world has become; and the question of what exactly it means to be “American” takes center stage.

“She used fashion as her way of having a conversation or dealing with the public,” said Sunita Kumar Nair, the author of “CBK: Carolyn Bessette Kennedy: A Life in Fashion,” to be published next month. The book focuses entirely on Ms. Bessette Kennedy’s style as seen through essays and interviews with designers, photographers and fashion figures. And now, when it comes to that conversation, fashion is talking back. Perhaps more than ever.

This fall, the brand Sporty & Rich published an ad campaign recreating some of the most famous paparazzi shots of Carolyn and John: walking their dog or his bike in the streets of TriBeCa in crew necks and boots, clutching hands and newspapers in jeans and flip-flops. On runways throughout New York Fashion Week and beyond, the building blocks of the C.B.K. wardrobe — white shirts, pencil skirts, jeans, loafers and pumps, slip dresses, men’s overcoats — dominated. The pieces were often referred to as “timeless” or “classic” or “understated,” but with just enough rigor to seem interesting.

Though anniversaries often inspire a reassessment of historic figures (next year will be the 25th anniversary of the plane crash), and despite the Kennedy family finding itself once again in the news (Robert F. Kennedy Jr. is seeking the White House, and a coming Ryan Murphy show will include a portrayal of Lee Radziwill, Jackie Kennedy’s younger sister), the C.B.K. revival is at once broader and more nuanced than that.

The Ubiquitous White Shirt and the 1990s

Like Diana, Princess of Wales, whose royal status, beauty and untimely death made her into a legend, Ms. Bessette Kennedy exists less as a person than an idea. Because she was so notoriously private, because she married into a family that had already colonized part of the public imagination, and because our memories of her are essentially preserved in amber (which is to say, a finite number of photographs, most of them taken between 1994, when she started dating Mr. Kennedy, and 1999), she will never age, get Botox, post an unthinking comment, get messy — or change her style.

Instead, Ms. Bessette Kennedy offered an example of a different way to be in the world, one that valorized what wasn’t shown. And because she never gave a single interview after her marriage, what she wore has become a stand-in for who she was.

That ethos has propelled her onto the mood boards of such disparate labels as Carolina Herrera and Sandy Liang; hovered in the air above the slip dresses and shirtdresses at Staud; and helped make the white button-up shirt the single most ubiquitous item of the season.

There were white artists’ shirts at Altuzarra, worn over full midi-skirts; crisp white shirts at Bally, paired with neat white pencil skirts; and asymmetric white shirts at Dior. There were long white shirts-cum-dresses at Peter Do, white shirts buttoned to the neck at Loewe and white shirts paired with the sort of boyfriend jeans Ms. Bessette Kennedy favored at Stella McCartney. That’s before you even get to the camel pencil skirts, another Bessette Kennedy staple, at Michael Kors, Gucci, MaxMara and Saint Laurent, to name a few.

“The woman this season is much quieter, less bold, with less nudity and fewer cutouts and leather ‘powerful’ looks,” said Alexandra Van Houtte, the founder of the fashion search engine Tagwalk. “She’s more discreet, also wears more wearable clothes, and colors on a whole have been a little bland: black, white, light blue” — which pretty much sums up the Bessette Kennedy palette, with the addition of gray.

Indeed, across more than 11,000 images from the last round of shows in Paris, London, Milan and New York, Tagwalk found a 45 percent increase in the number of shirts compared with spring 2023, and an 8 percent increase in white, Ms. Van Houtte said. “Minimalism” was up 46 percent, and the 1990s was the single most searched tag. (In the TikTok style channel, videos related to the 1990s have more than 93 million views.)

If Kate Moss represented the grunge side of the ’90s, Ms. Bessette Kennedy was its understated chic.

It was an aesthetic that married strong Social Register vibes (she wore headbands and even the occasional kerchief) with an appreciation for cut and material and a certain insouciance that never looked as if she was trying too hard.

“The Kennedys developed a style you could call casual but purposeful,” said John Hellmann, a professor of English at Ohio State University and the author of “The Kennedy Obsession: The American Myth of JFK.” “It seemed uniquely American but also modern in the best sense of the word. There was an economy to how they dressed. And Carolyn was in many ways the most updated version of that.”

At a time when New York fashion is undergoing one of its periodic paradigm shifts, with the big brands that once defined a national aesthetic giving way to a melting pot of new names with diverse identities and reference points, she represents a certain touchstone in the ontology of American style.

Mystery, Minimalism, Sustainability

“She was minimalism with character — she wasn’t sterile or boring,” said Wes Gordon, the creative director of Carolina Herrera, who, like many of the designers now channeling Ms. Bessette Kennedy’s style, knew her only through the imagery. He thinks of her, he said, when he is removing an extraneous ruffle from a shirt or otherwise toning down the label’s usual flamboyance. “I think I’ve seen every picture that exists of C.B.K.,” he said.

It’s this limited record that is part of her appeal, said Elizabeth Beller, whose book “Once Upon a Time: The Captivating Life of Carolyn Bessette-Kennedy,” a more formal biography, will join the Bessette Kennedy chorus when it is published next spring. “In the age of social media, where lives are often curated for show, Carolyn’s reserve is especially appealing.”

Professor Hellmann agreed. “In an age of extreme image replication and proliferation, there’s a mystery to John F. Kennedy Jr. and Carolyn Bessette Kennedy that gives them dignity,” he said.

She and Mr. Kennedy were one of the first celebrity couples to marry in total privacy in the age of tabloids and paparazzi, releasing only one picture they approved to the breathless public, who could not get enough of the simple silk slip dress Ms. Bessette Kennedy wore at her wedding — designed by the then-unknown Narciso Rodriguez, a friend from her Calvin Klein days, who did not remain unknown for long.

“She would never have been on the Vogue.com wedding website,” Ms. Liang said. “There’s something very special about that. The archive is the archive.”

Ms. Beller added that Ms. Bessette Kennedy “resonates with the cultural vibe of ‘stealth wealth’ and interest in sustainability.”

She might have worn Yohji Yamamoto or Prada, but, Ms. Nair said, “she only had, like, 30 to 40 pieces in her wardrobe” — unusual at a time when public figures are rarely seen in the same thing twice.

“You just think, ‘Oh, OK, that’s quite an edit right there,’” Ms. Nair said. “One of her friends said, ‘You’d open up her wardrobe, and there’s like, five black pants, a selection of really well-fitted shirts.’ The rest sometimes she would borrow if she needed to go to gala events.” She had a consistency that made her clothes feel as if they were “part of her psyche,” Ms. Nair said. As if she had chosen them, not a stylist.

Put another way: She had an Hermès Birkin, but it looked used, chock-full of the stuff of everyday life; she even toted it on the subway. That makes Ms. Bessette Kennedy an object of fascination not simply because of what she wore, but because of how she handled what she wore.

“I’m always wondering, ‘Would she wear this?’” Ms. Liang said. “Or what would she wear this with?”