On a nearly 90-degree September morning, Verena Adelsberger held her first pumpkin spice latte in a downtown Manhattan Starbucks. It wasn’t just her first of the season. It was her first ever.

Ms. Adelsberger, 25, who was visiting the United States from Zell am See, Austria, was moved to try the pumpkin spice latte, often called the P.S.L., after seeing it celebrated online for years. She took a sip of it, which she ordered as a Frappuccino, and grinned. “It tastes like cinnamon,” she said. “It’s very sweet.”

She rated it a seven out of 10, and then she left to catch the ferry to an equally classic piece of American culture: the Statue of Liberty.

Starbucks’ pumpkin spice latte, which turned 20 last month, has survived blistering political environments, harrowing global recessions and endless cycles of beverage and diet trends by refusing to be cool. Now, it’s a touchstone of the American palate.

The P.S.L. has evaded irrelevance by appealing to our need for a reliable marker of passing time. It offers a Pavlovian feedback loop: Give up a few dollars, receive instant nostalgia for chilly nights spent curled up watching “Practical Magic,” and a sweet reminder of the approaching holidays.

Before Starbucks unveiled its latte, “pumpkin” simply did not exist as a consumer category at the scale familiar to Americans today, said Erin LaBranche, a senior strategist at the global marketing company R/GA. This past year, pumpkin-flavored products accounted for $787 million in national sales, including pumpkin spice hummus and pumpkin spice deodorant, according to the consumer intelligence company NIQ. Peppermint-flavored products by comparison, brought in just $494 million in that same period.

While Americans have bought fewer pumpkin products over the last two years, the data company Bloomberg Second Measure reports that, this year, Starbucks’ sales increased by more than 7 percent during the week of the P.S.L.’s eyebrow-raising Aug. 24 debut.

A herd of copycats has joined it over the years, including a drink that Dunkin’ brazenly calls its pumpkin spice “signature” latte, which it began selling in 2020, and the rapidly expanding Blank Street Coffee’s shaken pumpkin spice cold brew, the shade of a chestnut mare.

The P.S.L. has not been without controversy: Its sugar content (50 grams in a medium), its ingredients (at first no real pumpkin and an allegedly carcinogenic coloring agent) and whether the formula secretly changes year to year have all spurred debate.

And then there is Starbucks itself, which critics have accused of union busting and abandoning its progressive “conscientious capitalist” roots, the P.S.L. merely a harbinger of plutocratic ruin. And in a warming climate, the P.S.L. may just force fans to consider the effects of their rampant buying.

Fall’s promise of new beginnings has long mobilized Americans. Starbucks did not manifest a devotion to autumnal spices out of thin air.

But Starbucks capitalized on it with a beverage that was, for an American coffee conglomerate in 2003, innovative. Executives debated various seasonal flavors, including pumpkin, honey-nut and maple-pecan, said Peter Dukes, a Starbucks director of market strategy better known as the “father of the P.S.L.”

“We thought, ‘This one was so unique, give us a chance to develop what it tastes like in the cup’ — and you keep pulling the thread.” At the time, pumpkin scored significantly lower than chocolate and caramel on customer surveys.

Starbucks debuted the drink in roughly 100 locations across Washington, D.C., and Vancouver, British Columbia, but almost immediately, “you could hear the excitement in store managers’ voices,” Mr. Dukes said. The next year, the pumpkin spice latte went national, and soon Katy Perry and Kristin Cavallari — avatars of a certain kind of early aughts American celebrity — were praising P.S.L. season for free.

But the pumpkin spice latte was never exactly hip. In fact, its unwillingness to align with the whims of a mercurial pop culture has become integral to its success. Acolytes across the country and world reach for the pie-flavored drink because it forgoes the effort so many consumer products put in to signal sophistication. It’s a seasonal trend, but it is not trendy.

That was by design. “We were casting a broad net in terms of bringing people into coffee culture,” Mr. Dukes said. Accordingly, Starbucks engineered the P.S.L. for maximum eyeballs. Thomas Prather, vice president of brand and product marketing for the company, described the first marketing efforts for the drink as “fun” and “irreverent.”

Indeed, early advertisements relied on jokes about excessive enthusiasm for fall. In one from 13 years ago, a redheaded man in a chunky white turtleneck and green apron rants to a customer about how he loves this time of year. “He doesn’t really work here,” a Starbucks manager says to the customer. “It’s Pumpkin Spice Latte time: Who’s not excited?” reads text that follows.

As the P.S.L. tightened its vise grip on fans of fall, the term “basic,” a precursor to Christian Girl Autumn, took hold online. Basic — which Maggie Lange explained in a 2014 article for The Cut had been co-opted from the comedians Lil Duval and Spoken Reasons, as well as a handful of songs — referred to an abject lack of originality, a tragic genericism, an unabashed love for mass-market items like Ugg boots and “Live, laugh, love” art.

Often, women deployed it to denounce the tastes of other women. The term was criticized as reinforcing patriarchy and perpetuating class anxiety — but not before the P.S.L. became, as Ms. Lange wrote, “a key motif” in the derogatory portrait of the basic woman.

Perhaps that’s because Starbucks had by then become ubiquitous, growing to 16,680 stores from 1,886 between 1998 and 2008, or because the P.S.L. had mutated into an emblem of treating oneself.

“A lot of people will say it’s a ‘basic’ white girl thing,” said Jennifer Rominger, a public-school teacher in West Texas, of the latte. By the time she procured her first P.S.L. of the season on release day, Ms. Rominger, 38, had already ordered a Halloweentown sweater and made plans to visit her local pumpkin patch for a photo shoot.

“People are throwing around ‘basic’ like it’s derogatory,” she said. “I don’t think it’s the term that appeals to me, but I do fit that stereotype. I go into this persona in the fall because it’s a mood.”

Instead of shying away, Starbucks has leaned into an image defined by customers. “One of the big things about relinquishing control is having strong and tight opinions but held loosely,” said Rachel Pool, the head of strategy for the marketing firm Ogilvy. “What of the narrative do you want to own, and what parts are you willing to allow for consumers, culture at large to really run with?”

On P.S.L. release day this year, Starbucks posted a TikTok video in which a woman takes a sip of the latte and immediately dons flannel and a knit scarf to lay in the center of a heart made of small gourds.

Ms. Pool compared the way Starbucks let the P.S.L. take on an identity of its own to a more recent beverage spectacle, the Grimace Shake from McDonald’s, which became a cultural sensation last summer when Gen Z made it the central prop in absurdist horror shorts on social media.

With the Grimace Shake, consumers intentionally subverted a big corporation’s marketing message, but both parties still won. The Pumpkin Spice Latte has played that game for 20 years.

Victoria Carlotti, a fashion student at the New School, would never post about the P.S.L. — Starbucks is a bit “cringe,” she said. But, recently, at a Starbucks Reserve Roastery in Manhattan, she said she planned to drink an uncountable number of pumpkin spice lattes this fall.

Ms. Carlotti, 21, reaches not for the newer, hyper-customizable variations that Starbucks dangles in front of Gen Z customers, but for the classic hot version. “It’s nice to have something that keeps you consistent,” she said. “Your brain realizes it’s been another year.”

Ms. Rominger, the schoolteacher, agreed. “It turns the rhythm of life into a positive thing,” she said. “That’s what people are looking for.”