Scores of Canadians openly rolled, smoked, vaped and rhapsodized over their legally bought weed for the first time Wednesday as a seismic cultural shift ushered in a new era of how cannabis - and cannabis users - are regarded across the country.

While much of the day unfolded as a typical mid-week workday for many, there were signs of a monumental milestone being crossed: the pungent odour of marijuana wafting along Montreal's boutique-lined Ste Catherine Street, the appearance of furry costumed characters passing a massive joint while cavorting in a Toronto park, a full-page newspaper ad by an investment firm touting the economic potential of a “budding industry.”

After nearly a century of prohibition, the dawn of legal recreational marijuana was met with jubilant celebration by longtime advocates, but also opposition by some protesters who dared to challenge the new norm by raising fears about health and safety concerns.

For many, the day was one of celebration.

The smell of weed hung heavily along Montreal's main shopping drag, where a lineup of hundreds of would-be patrons stretched down the block in front of a government-sanctioned pot shop. Cheers erupted when doors opened and some among the giddy crowd cheerfully demonstrated joint-rolling techniques to reporters.

“It's pretty magical,” said 39-year-old Hugo Senecal, who showed up with Corey Stone at 3:45 a.m. to be part of what they called a historic moment.

“It's like Christmas, New Year, my birthday and Easter all in one day. For a stoner it's kind of a good moment.”

The 32-year-old Stone said he hoped legalization would help dissipate some of the stigma around cannabis, especially in a province that has some of the most restrictive laws around usage, possession and promotion in the country.

“You can see it from people walking by,” he said of the disdain that lingers for some. “Some are smiling, but some are shaking their heads.”

Hundreds of supporters gathered at Toronto's Trinity Bellwoods Park and cheered when the clock struck 4:20 p.m., a number synonymous with cannabis culture. Many smoked openly and danced alongside two pot-themed mascots - a caped blue, red and yellow crusader known as “Bongman” and a weed-inspired take on Polkaroo that its creator Mark Scott called “Tokaroo.”

Over in free-spirited Kensington Market - home to artists, vintage clothing stores and independent grocers - cannabis users crowded around a cardboard-covered pool table to grind weed, roll joints and smoke from bongs at the HotBox Lounge + Shop.

That followed an early morning “wake and bake” on trendy Queen Street West, where a handful of stoners held an “End of Prohibition Party” at the Friendly Stranger pot culture shop in advance of a day full of giveaways, discounts and demonstrations by various weed-friendly businesses.

Shop proprietor Robin Ellins predicted that legalization will “legitimize” a flourishing cannabis culture that had long been forced underground, and possibly broaden its appeal to new users.

“We spent the last quarter-century working very hard every day in order to make this day happen, and it's finally here,” said Ellins.

“There's been hundreds of 18-hour days over the years, but to actually see this change happen in Canada, it's a monumental event. This is a once-in-a-lifetime event. We've taken 100 years of prohibition and put it behind us, and now we're starting a new journey.”

In Halifax, customers browsing a pristine downtown shop described a clinical atmosphere that nonetheless offered a liberating experience. Buyers took their brown-bagged purchases two blocks over to an outdoor “toking spot” next to a car parkade.

“So many people have fought for so hard, for so long and now all their efforts have come to fruition and now I get to enjoy this,” said Connor McKechnie, a university student who lit a pre-rolled joint in front of a national television network audience.

Longtime advocates touted changing mores and greater mainstream acceptance for the radical shift in policy, bolstered by unrelenting hype from entrepreneurs heady from the possible green rush of a budding market.

Some of Canada's most famous weed supporters tweeted their elation Wednesday, including Vancouver movie star Seth Rogen who declared from his verified account: “Few moments in my life have brought me pride like I feel today. Canada, I love you.”

The Trailer Park Boys added from their verified account: “Weed is legal!! Let's go to the weed store!!!” while Olympic snowboarder Ross Rebagliati, famously stripped temporarily of his gold medal after testing positive for cannabis at the 1998 Nagano Games, tweeted a terse: “Congratulations Canada.”

The events followed late-night celebrations Tuesday in which revellers rang in the new era with marijuana-fuelled cheers, honking horns, bar lineups and smoky sidewalks in downtown Toronto.

Hundreds rang in the new era with a New Year's Eve-style “bud drop” at one nightclub, where a massive doobie dropped from the ceiling at midnight.

But while many welcomed the new regime, a coalition of groups concerned about health risks tried to share their message from the steps of the Vancouver Art Gallery, as pro-pot hecklers shouted over them.

Pamela McColl of Smart Approaches to Marijuana Canada said she believes legalization normalizes a dangerous substance and called for a ban on smoking marijuana in any multi-unit residence and anywhere that children live.

“It is a very, very dark day for Canada,” she told a crowd of gathered media.

“The damage that is going to ensue from this policy change will be horrendous in terms of drugged driving, cognitive damage to children, more addiction, more costs. The list goes on.”

Across Robson Square, Topher Graham and Tristan Risk said they took the day off work to celebrate, with Risk saying she no longer has to feel guilty about smoking weed.

“I like that I can do it legally, safely and publicly. I don't have to feel like sneaky teenager anymore.”