The 20th of April — it’s a hazy holiday that marijuana enthusiasts have been celebrating for decades.

The date is in recognition of the number 420, which for reasons not entirely clear has been a symbol for stoners the world over.

Its origin story, according to legend and numerous investigations, is that there was a crew of teenagers from California in the 1970s who used to meet to toke up at 4:20 p.m. outside their high school. It caught on. The number “420” became a slogan that’s made its way onto T-shirts, Tinder profiles and rebellious screen names for what seems like forever.

For this year’s unofficial high holiday, it’s not hard to find celebrations of all kinds in Boston. There’s a 420 Comedy Show at the Limelight Comedy Club, parties sponsored by stoner culture-inspired clothing companies, and a Harvard-affiliated discussion on the latest in marijuana science at the Aeronaut Brewery in Somerville as part of the Cambridge Science Festival.

REALTED: Massachusetts’ anti-legal pot campaign focusing on kids

But now that Massachusetts seems closer than ever to making afternoon smoke sessions fully legal — voters will decide on whether to green light recreational use of the drug in November — there is one group conspicuously not taking part in the revelry: the Campaign to Regulate Marijuana Like Alcohol.

“We just don’t have anything planned for 4/20,” Jim Borghesani, spokesman for the group, which is leading the legalization ballot campaign in Massachusetts, said in a Tuesday interview. “We have plenty of things planned as the campaign is moving forward, just nothing for tomorrow.”

Borghesani said the campaign isn’t focusing on rallying the base of marijuana users or mobilizing the activists who’ve been calling for full legalization in the state for decades — or, for example, celebrating the stoner community’s big day with them.

A rival, more libertarian legalization campaign called Bay State Repeal, which is now defunct, had gained some early support from pot activists.

He said, though, that many who rallied for legal pot in the past are supporting CRMLA’s efforts and will continue to do so.

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Among CRMLA’s chief arguments is that if alcohol is legal, and can be sold and taxed with government oversight, marijuana should be legal, too.

“That’s sort of the messaging that has been within certain advocacy groups for decades. It’s something that we hope to broadcast to a much larger population so they can take an intelligent look at prohibition and how it has failed,” Borghesani said.

After all, it’s the average voter the campaign has to reach, he said, not the comparatively small group of passionate pot users, who are — mostly — on board anyway.

“If we just have their votes, it wouldn’t be enough in Massachusetts, and even they know that.”

Recent polling suggests CRMLA’s message is resonating with a majority in the state, but an opposition campaign helmed by Mayor Marty Walsh, Gov. Charlie Baker and other top politicians is in the early stages. The group, the Campaign for a Safe and Healthy Massachusetts, is sounding alarms about the impact of legalization, particularly the risk of exposing more children to the drug.

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