Ah, April 20th. The international counterculture holiday where weed aficionados the world over light up a joint in celebration of cannabis (preferably at 4:20 PM). From San Francisco, California, to Dunedin, New Zealand, pot smokers have long used 4/20 as an excuse to get high. But why? Why is 420 National Weed Day?

At Hop Culture, we usually bring you the latest and greatest from the world of craft beer. But as young, socially liberal professionals in an industry where pot is as frequently shared as pilsner, we thought it’d be fun to deep dive into the age-old question: What is 420 and what does it have to do with weed?

The Rumors Behind The Origins of 420

“It’s the police radio code for a situation involving cannabis.”

If you’ve ever discussed the origins of 420 with a group of people, some well-meaning individual probably tossed out this explanation. It’s not correct. In the United States, most police use 10 codes, a system first developed in 1940 by the Association of Public Safety Communication Officials (APC).

Ever hear somebody say “10-4”? That’s an affirmative acknowledgment. “10-24”? That’s a mission completion. Within this system, there is no 4 that isn’t preceded by a 10.

Perhaps — PERHAPS — someone might’ve been referring to the California Penal Code, which does have a coding system that begins with 4. But even within that coding system, 420 has nothing to do with pot.

There are others who think the number comes from California Senate Bill 420, often known as the Medical Marijuana Program Act, which John Vasconcellos introduced and Governor Gray Davis signed into law in 2003. But the bill was named for the 420 holiday, not vice versa.

The Prevailing Theory Behind 420

Although disappointing, no one actually knows how 420 became synonymous with weed. But the prevailing theory involves a group of friends from San Rafael, California, who used the phrase “420 Louis” to mean they’d meet by the Louis Pasteur statue outside their school to get high at 4:20 PM.

The nickname probably would’ve died there, except that one of the kids’ brothers was friends with Grateful Dead bassist Phil Lesh. So the kids started smoking weed with the Grateful Dead, who rehearsed in San Rafael.

When your pothead friend makes up a nickname for something, it most likely doesn’t escape your friend group. But if Jerry Garcia and Phil Lesh pick it up? It most certainly wouldn’t be the first time the Grateful Dead influenced pop culture.

So Why Is 420 National Weed Day?

Although there are many rumors behind the 420 nomenclature, the most likely theory is that the name started with a couple high school friends in San Rafael and gathered steam after it hit the Grateful Dead.

Regardless of where the name comes from, the pseudo-holiday is a fun excuse to take a break. Even if you don’t imbibe, it’s a great reason to relax and get together with friends.

Perhaps the most famous 420 celebrations happen in Denver, Colorado, at Civic Center Park, and on the campus of the University of Colorado Boulder. In Northern California, people tend to congregate on “Hippie Hill” in Golden Gate Park or in Dolores Park. Canada is also a popular place to celebrate, with smokers gathering at the Mount Royal Monument in Montreal and the Parliament Hill in Ottawa.

This 4/20, at 4:20 PM, if you see a cloud rising above one of your city parks or landmarks, it’s probably not a fire — just a bunch of friendly people partaking in a unique and fascinating piece of human culture. And now you know why.

Check out a few of our favorite places to celebrate: SlickVapes, SmokeCartel, Diamond CBD, and Karma Not Pharma.

Liked this article? Sign up for our newsletter to get the best craft beer writing on the web delivered straight to your inbox.