420 refers to weed because a group of California high school kids in the early 1970s used “420” as a secret code for meeting up to smoke cannabis at 4:20 p.m., and that inside joke slowly spread into global cannabis culture. Over time it came to mean both the time (4:20), the date (4/20, April 20), and, more broadly, anything related to marijuana.

Why does 420 refer to weed?

Quick Scoop

The short version

  • In 1971, five students at San Rafael High School in Marin County, California, would meet after school at 4:20 p.m. by a statue of Louis Pasteur to smoke cannabis.
  • They started using “420” as a code word so teachers, parents, and others wouldn’t know what they were talking about.
  • Their friend group had connections to the Grateful Dead scene, which helped the term travel through music circles, underground culture, and eventually mainstream cannabis culture.
  • Today, “420” is global slang for weed, the act of smoking it, and the unofficial stoner holiday on April 20.

The origin story: “The Waldos”

A widely accepted version credits a group of five high school friends known as “the Waldos.” They supposedly got the nickname because they often hung out by a wall at San Rafael High School.

  • In 1971, they heard about an abandoned cannabis patch near Point Reyes and decided to search for it after school.
  • Their meet‑up time: 4:20 p.m., chosen because sports and extracurriculars were over and it was late enough not to look suspicious.
  • Their meet‑up spot: a Louis Pasteur statue on campus.
  • To plan or remind each other, they’d say things like “420?” or “420 Louis,” which quickly got shortened to just “420.”

Even though they never found the mythical weed field, the code stuck within their circle as shorthand for smoking cannabis.

How 420 went from inside joke to worldwide slang

At first, “420” was just local teen slang, but a few specific cultural pathways amplified it.

  1. Grateful Dead connection
    • Some of the Waldos had family or social ties to people in the Grateful Dead’s circle, and they spent time around rehearsals and shows.
 * As band followers and roadies picked up the term, it moved into the wider Deadhead community, which was already strongly linked to cannabis culture.
  1. High Times magazine boost
    • By the 1990s, the cannabis‑focused magazine High Times began using “420” in print and promoting April 20 gatherings, treating it as an established weed reference.
 * That national (and international) exposure locked “420” into stoner vocabulary and helped turn 4/20 into an annual cannabis celebration.
  1. Pop culture, internet, and memes
    • As cannabis references became more visible in movies, TV, music, and later on the internet, “420” showed up on posters, usernames, and jokes.
 * The number eventually became a kind of password or badge: if you “get” 420, you probably know weed culture.

What 420 means today

Now “420” has a few overlapping meanings in everyday use:

  • Time of day :
    • “It’s 4:20” can be a playful or literal cue that it’s time to smoke.
  • Date (April 20 / 4/20) :
    • April 20 is treated as an unofficial cannabis holiday, with rallies, festivals, and store promos in many cities.
* Some events also frame it as a day for legalization activism, not just partying.
  • General code for weed :
    • “420‑friendly” in rental ads, dating profiles, or roommate posts means someone is okay with cannabis use.
* “420” on merch, gamer tags, or comments often signals a relaxed or rebellious cannabis vibe.

In short, it evolved from a secret time and place to meet, into a broad symbol of cannabis lifestyle and acceptance.

Popular myths (that aren’t true)

Over the years, a bunch of explanations for 420 popped up, but most are just myths. Common incorrect theories include:

  • It’s a police code for marijuana.
    • Different departments use different code systems, and there is no universal “420 = weed” police code.
  • It’s the number of chemical compounds in cannabis.
    • Lab research doesn’t support a neat “420 chemicals” count; active compounds like cannabinoids and terpenes don’t line up with that exact number.
  • It’s tied to Bob Marley’s birthday or death.
    • His birthday is in February, and his death was in May, so the dates don’t match April 20.
  • It comes from Bob Dylan’s song “Rainy Day Women #12 & 35,” because 12 × 35 = 420.
    • The math works, but there’s no solid evidence this inspired the slang; this connection is usually treated as a fun coincidence.

These stories are catchy and easy to repeat, which is why they still circulate, but historians and cannabis writers consider the Waldos’ 4:20 p.m. meet‑up origin much more credible.

420 as a cultural symbol now

As cannabis has moved from taboo to mainstream debate, “420” has shifted from secret code to cultural marker.

You’ll see it used as:

  • Identity signal
    • Phrases like “420 friendly” or “420 lifestyle” indicate comfort with cannabis as part of daily life or social identity.
  • Rebellion and counterculture
    • For some, 420 still represents resistance to strict drug laws and a nod to decades of underground cannabis use.
  • Marketing and legalization politics
    • Brands, dispensaries, and events heavily use “420” in promotions, especially around April 20.
* Advocates sometimes use big 4/20 gatherings to push for policy reform, decriminalization, or medical access.

So when you see “420” on a poster, username, or T‑shirt in 2026, it’s carrying 50+ years of in‑joke history, music‑scene lore, and evolving cannabis politics with it.

TL;DR:
420 refers to weed because a small group of California teens in 1971 used “420” as a secret 4:20 p.m. meet‑up code to get high; through the Grateful Dead scene, magazines, and pop culture, that code spread worldwide and turned April 20 (4/20) into the unofficial cannabis holiday and “420” into shorthand for marijuana itself.

Information gathered from public forums or data available on the internet and portrayed here.