If you’ve ever discussed the genesis of “420” with fellow weed smokers, you’ve likely heard a few stories/theories/loads of bullshit about it. Let’s face it, most stoners will rationalize their hypothesis into anything. It’s part of the storytelling hubris that comes with pot. Some of the most widespread conjectures include being the police radio code for marijuana (it isn’t, yet interestingly enough it is the actual police code for murder in both the Las Vegas Police Department and the show CSI); the number of chemical compounds in cannabis (which is really 315); the presumed “tea time” in Holland (not officially, though it sounds like a fine time for tea); or even Adolf Hitler’s birthday (the date is correct, yet it has nothing to do with the late Führer, which is probably for the best, since Hitler’s not the first person we want in mind when we’re high).

So why is it such a popular code at this point? It’s become a way to reference marijuana everywhere. When looking for an apartment or roommate, the term “420-friendly” has become standard. “420” themed parties happen daily all over the world. Last year, I was hanging out with this Russian girl I know; her English is limited, and lots of expressions can go over her head, yet when she wanted someone to smoke her out, she very naturally asked if I “had any 420”. It is that popular. Someone might not know how to properly use articles or get most Western pop culture references, but still be aware of “420.”

The real story behind “420” goes back over four decades, to the fall of 1971. In the Northern California town of San Rafael, a group of teenagers who called themselves the Waldos and shared a strong cannabis-based bond, heard about an abandoned marijuana crop around the nearby Coast Guard station. Like roughly 100% of teenage weed enthusiasts would after hearing about this, the Waldos set out to score some of that huge stash. They agreed to meet by a Louis Pasteur statue that was right outside San Rafael High School at 4:20 in the afternoon. “4:20 Louis” became a quick way to remind each other of their daily plans. For weeks they would meet at the Pasteur statue, get in a car and smoke away while they rode all over the Point Reyes Peninsula in search of the Promised Land (or at least a plant or two).

Of course, they never found the damn crop, but the routine and the drive was probably a good thing for them (it’s really about the journey, isn’t it?), and the whole thing created, at least, a cool reference for weed at all times. It could mean a request for pot, or an offer, or simply inquiring whether the other person was high. No authority figure got the reference, so just saying “4:20” became a comfortable way to discuss their priorities and undertakings.

But this was still a pretty discreet piece of inside information, so how did this term manage to develop from the casual slang of a small group of Bay Area teenagers to the well-known global code for marijuana?

Well, just like the concept of jam bands, pre-concert parking lot activities, Douglas Coupland’s career and the global ice cream game, it was touched and forever changed by The Grateful Dead.

You see, the Dead had just relocated to Marin Country, and had a practice space that was pretty close to the boys’ high school. Naturally, this became an ideal spot for the Waldos to hang out, smoke some dro, and listen to the band rehearse songs. The atmosphere, as most Dead-related environments at the time, was very welcoming. So the kids were part of the whole scene, and the term “4:20” was catchy enough for any Dead associates to start saying it, too.

If there’s anything that Grateful Dead’s fans have — aside from a tie-dye obsession – it is loyalty. Some people have been following the band through their five decades of existence, and have seen them play live hundreds of times. The actual “show” part of a Grateful Dead concert is known to be just another fragment of the experience. Socializing — and a big share of that includes drug use — is an important element of their tours. So, a decade or so later, Dead-heads all over the country had started using the slang “4:20” to refer to marijuana.

After that, it was easy. The popular cannabis magazine High Times was referencing the term by the early 90s, and later on they bought the website 420.com. Saying “420” became as international as any term or expression can get, regardless of the language you were speaking. Ganja is a universal tongue. 4:20 in the afternoon is often used as a good time to smoke (and when yours truly can’t sleep, 4:20 in the morning has been a recurring hour, as well). April 20th has unofficially developed into the International Weed Day, which hosts festivals and celebrations in its honor every year in many cities around the globe.

It’s interesting how California has been such a catalyst for anything cannabis-related. Not only was the “420” term coined there, but they were the first State to establish a medical marijuana program (enacted in 1996’s Proposition 215, and later on with the appropriately named “Senate Bill 420” in 2003). They also happen to have arguably the best bud on the planet — this is not just my opinion; legendary reefer connoisseur Snoop Dogg happens to agree.

So from Long Beach (because a shout out to Snoop is only appropriate) and San Rafael to the most remote places in the world, this 4/20 may just see enough puffing to power a Jerry Garcia resurrection. Does that have any major significance when retracing the story back to the Waldos? Probably not that much, but do you honestly need another excuse to get high?

Some rituals are just nice to have.