In 1971, five high school students – Steve Capper, Dave Reddix, Jeffrey Noel, Larry Schwartz, and Mark Gravich – in San Rafael, California, calling themselves the Waldos because "their chosen hang-out spot was a wall outside the school", used the term in connection with a 1971 plan to search for an abandoned cannabis crop that they had learned about, based on a treasure map made by the grower. The Waldos designated the Louis Pasteur statue on the grounds of San Rafael High School as their meeting place, and 4:20 p.m. as their meeting time. The Waldos referred to this plan with the phrase "4:20 Louis". After several failed attempts to find the crop, the group eventually shortened their phrase to simply "4:20", which ultimately evolved into a code-word that the teens used to mean consuming cannabis.

Mike Edison says that Steven Hager of High Times was responsible for taking the story about the Waldos to "mind-boggling, cult-like extremes" and "suppressing" all other stories about the origin of the term. Hager wrote "Stoner Smart or Stoner Stupid?", in which he attributed the early spread of the phrase to Grateful Dead followers – after Reddix became a roadie for the Dead's bassist, Phil Lesh – and called for 4:20 p.m. to be the socially accepted hour of the day to consume cannabis.

Solarpunk is a movement focused on a positive, ecological vision for a future where technology is used for human-centric and ecocentric purposes. It is a literary, artistic and aesthetic sub-genre and is also closely tied to eco-political activism. Solarpunk narratives have a distinctly positive and utopian foundation in contrast to the often dystopian visions found within other "punk" science fiction genres.

So far the majority of you are incorrect.
420's origin IS known.
the term 420 originated at San Rafael High School, in 1971, among a group of about a dozen pot-smoking wiseacres who called themselves the Waldos, who are now pushing 50. The term was shorthand for the time of day the group would meet, at the campus statue of Louis Pasteur, to smoke pot. Intent on developing their own discreet language, they made 420 code for a time to get high, and its use spread among members of an entire generation.
So there ya go, someone's parents out there invented the term 4/20.
And remember this:
There are NOT 420 chemicals in Weed. It's about 315, the num. goes up or down depending on what you're smoking.
4/20 is NOT police code or Maryjane.
And that whole shit about Holland and 4/20 over there being "tea time" for smokers isn't true either.

I know my shit.

Best holiday(which is today, april 20th)!

national weed smoking day. light em up at 4:20 pm or am.

Common misconceptions point to crazy theories about weed but the truth is it is actuly a number between 419 and 421.

One of the many names for weed. Its mainly in reference to time. But theres also April 20th.