Waiters glided between tables outside a small Italian restaurant in the still-roasting Brooklyn evening sun. Plates empty, conversation meandering, I leaned back in my chair and got the first inkling that I was losing my mind.

The trigger had been innocuous enough: a small, piña colada-flavoured gummy popped just after dinner at the encouragement of a well-meaning friend. She’d hoped, reasonably enough, that a little weed-infused edible would enhance my experience of the concert we were heading to next. Now, with what felt like an industrial-grade concentration of marijuana’s active ingredient, THC, coursing through my bloodstream (I later learnt it was one of the smallest doses it is possible to buy in a single edible product), my hair was exploding into a sweaty bouffant, and I had all but left Planet Earth.

The experience lasted for the duration of the two-hour show that June night and required me to sit ignominiously in the dirt of Prospect Park doing my best not to pass out. As a thousand tweens swirled joyfully around us, my friends patted me reassuringly on the head while exchanging looks of concern as if I were a senior citizen who had wandered into a rave.

I’ve had my share of encounters with London parties over the years, but nine months after relocating to New York in my early thirties — and well into my hedonistic retirement — it hadn’t crossed my mind that a small yellow sweet would be my undoing. My gummy faux-pas turned out to be emblematic of several jarringly broad cultural gaps I have stumbled upon since moving across the Atlantic, from the well-documented differences in humour and language to less predictable wrinkles in politics and taste, even among generally like-minded peers.

Weed came to symbolise a deeper chasm between our worlds, and one that, having never taken more than a few puffs in my life, made me feel slightly shamefully out of place. Most Americans are familiar with the UK’s quasi-pathological relationship with alcohol, but I was unprepared for their equivalent: the colleagues who routinely “popped a gummy” as soon as they got home from work; friends who take trips to legal out-of-state dispensaries to replenish their dwindling stashes; the tasteful little receptacles you find in grown-up, mid-century-furnished Brooklyn apartments.

As it happened, the blossoming of New York’s weed scene coincided neatly with my arrival. On March 31 2021, then-governor Andrew Cuomo signed a bill into law that made it legal for people over the age of 21 to smoke marijuana and for licensed businesses to sell it, ending decades of frustration on the left and bringing the state into line with 15 others that had done the same.

On my first trip north out of the city that October, I was staggered to see huge road signs reading “Don’t drive high”, an advisory that to me would feel so redundant in genteel Britain it might as well say “Don’t drive blindfolded”. “There’s this weird assumption in the UK that you grow out of weed,” a thirtysomething New York friend and gummy aficionado told me when I asked her to explain marijuana’s differing presence in our cultures. “That isn’t really a thing here.”

When I’ve talked to friends from home about my New York experience, the expression that has most readily come to mind is “uncanny valley” — a term originally used in aesthetic philosophy to describe the unease people feel when they encounter humanoid robots that resemble them closely but imperfectly.

When I arrived in New York, I was struck by how similar it was to London, but always just a degree out, from the anachronistic transportation system to the relative lack of complaining about the (arguably more irksome) weather. The thing that hit me most immediately and viscerally, though, was the smell — that inimitable, fruity aroma of marijuana, which seemingly pervades every street corner, grocery store, apartment building and public park in New York but is barely detectable across vast swaths of London (Camden Market and the Notting Hill Carnival being notable exceptions).

Data for cannabis consumption globally is scarce, complicating comparisons between countries. But the most recent figures from the US Centers for Disease Control, from 2019, show that 18 per cent of Americans said they had used marijuana at least once during that year. According to the UK’s Office for National Statistics, in March 2021 just 5.8 per cent of British adults aged 18 to 59 reported using the drug in the previous year.

For New York City, the last data point on recreational cannabis use from the NYC Department of Health was from 2015-16, before the drug was legalised, indicating that 16 per cent of New Yorkers said they had smoked weed in the past year, up from 13 per cent in 2003-04. According to Grand View Research, New York’s cannabis market is expected to be worth more than $7bn by 2025. If the smell is anything to go by, it’s already well on its way. At a press conference outside New York’s City Hall in July, mayor Eric Adams told reporters with a laugh: “The number one thing I smell [in the city] is pot. It’s like everybody is smoking a joint now.”

The ascent of weed in New York marks a new chapter in the city’s relationship with drugs, which has largely mirrored the ebb and flow of economic and cultural forces. If the trading-floor cocaine of the 1980s and the club kid ecstasy of the 1990s gave way to the less visible ravages of the opioid epidemic, the New York that has emerged from the pandemic is something else again: a weed town, diminished by collective trauma but furtively remaking itself.

In a bid to understand the hold that marijuana has on post-legalisation New York, I head one sweaty Tuesday in July to the place I most associate with the weed crowd: Washington Square Park in Lower Manhattan. The little quadrangle has long served as a hub for Manhattan’s unofficial pot business, hosting a growing array of independent sellers.

Despite the fact that no sales licences have yet been issued in New York, and the state has sent out 52 cease-and-desist letters to unlicensed outlets so far, the mostly young, male vendors appear cheerfully unfazed by passing police officers. “Pre-rolls, edibles, flowers!” a man in cartoonishly baggy shorts calls out from behind plastic tables groaning under marijuana-related wares.

If the sellers are troubled by anything, it is journalists. When I approach a man with a brightly coloured beard manning one of the stalls, he politely declines my request for an interview and warns me that other vendors may not be so friendly. “We’ve been getting a lot of heat because of the media attention,” he says disapprovingly.

Across the park on a bench under a copse, I meet Gabriel, a 17-year-old from Florida with a giant plume of frizzy mouse-brown hair. He tells me he just bought two pre-rolled joints in the park for $15, which he declares a “pretty good” price. “Miami doesn’t have legal weed,” he says thickly between tokes. “There’s so much more smoking here.”

Despite the slow rollout of licensing in the state, the cannabis industry has been betting on legalisation in New York for years. Some of the biggest weed companies in the US have set up shop in the city already, offering medicinal marijuana and other products containing legal derivatives in anticipation of eventually gaining permission to sell the real thing.

In midtown Manhattan that afternoon, I drop by a sleek dispensary called MedMen, which has been on Fifth Avenue since 2018. Part of an upscale chain whose minimalist outlets appear to be modelled on Apple stores, the shop is adorned with racks of red-and-white branded hoodies and track jackets, while huge display tables with inset lights offer details of its range of high-end products (Wellness Gel capsules, $50 a pack; Releaf Hemp Infused Balm, $79.99).

Parked haphazardly around the nearby streets, meanwhile, are at least half a dozen green trucks belonging to a scrappier-looking outfit called Weed World, emblazoned with advertisements for items such as “trippy treats” and “potcorn”. Weed World’s owner, who goes by Dr Dro, tells me later that the company began retailing weed-related products here a little over four years ago, though he insists they are within the legal limit for THC. Legalisation, he claims, has led to a flood of upstart competitors who are often less diligent about toeing the legal line: “The biggest difference [has] been more street vendors. People setting up tables and cannabis stores popping up.”

When I stop at a Weed World truck on Fifth Avenue, the sales assistant at its open window wobbles alarmingly in her chair and says she’s “too high right now” for an interview. I have more luck with Chee, an 18-year-old in another Weed World truck a few blocks down, who also appears pretty high but is compos mentis enough to sustain a short conversation. “I feel like for a while weed was thought of as something that wasn’t OK, like a ‘drug’ drug,” she says when I ask how the scene has changed in the past year. “But now that it’s legalised, people just see it like alcohol.”

New York is by no means the capital of America’s weed culture. In February, I found myself walking in the warm spring sun along the boardwalk of Venice Beach, California, where recreational cannabis use has been legal since 2016, picking my way through a string of makeshift stalls selling bongs and Bob Marley knick-knacks. According to the California Department of Public Health, the number of adults who said they’d used cannabis in the previous month in the state jumped from 10.8 per cent in 2015-16 to 15.1 per cent in 2019-20.

It struck me there that perhaps weed, like alcohol, is a modern inevitability. That any culture facing a climate emergency, decaying public institutions and seemingly irreconcilable political differences will eventually turn to its most widely available sedatives. In May, London’s centre-left mayor Sadiq Khan announced he had appointed a drug tsar tasked with reviewing the UK’s substance abuse laws, arguing, after touring a cannabis factory in Los Angeles, that “the illegal drugs trade causes huge damage to our society”.

But something in the uniquely anxiety-inducing nature of life in New York City, from the apocalyptic concentration of rats to the spiralling housing costs, seems to lend itself to seeking a means of chilling out. “I think more people are smoking weed to escape the reality of the truth, every day facing life,” a man called Jonathan told me in Washington Square Park, holding a spliff of such girth it brought to mind Withnail and I’s “Camberwell carrot”. “They use the drug to escape.”

For the final stop on my weed tour, I head across the Hudson river west of Manhattan into the leafy suburb of Maplewood in New Jersey, a state generally better known for commuters than cannabis. But since the state legalised recreational marijuana last year, Maplewood is now home to one of the handful of dispensaries licensed to sell it, and therefore an unlikely mecca for weed-lovers making pilgrimages across the river.

An imposing white building on an otherwise sleepy street, The Apothecarium is humming with activity when I approach, as a surprising range of customers — I spot several elderly couples — streams through its doors. After being allowed in by an imperious security team wielding ID scanners like nightclub bouncers, I find myself in a lavish space that has the feel of a stoner concept store, dotted with tastefully presented weed products as far as the eye can see. I buy a small $30 pack of sour- watermelon-flavoured edibles and head back to New York to sample them, hoping that this time I can crack the dose necessary to match my lamentable tolerance.

Sitting on the roof of my Brooklyn apartment building in the low evening sun, I carefully tear one of the sweets in half and pop it in my mouth. For a few minutes, nothing. Then, slowly, a rising heat. A curious feeling of separation from space and time. And gently pervading it all, a deep sense that everything is going to be just fine.

India Ross is an FT news editor in New York

Follow @FTMag on Twitter to find out about our latest stories first