What does 420 mean? 420 is shorthand for cannabis culture, and by extension for 20 April, the date on which that culture celebrates itself worldwide. The most widely documented account traces it to a group of high-school students in California in the early 1970s who used “4:20” as their meeting time. The many other explanations in circulation, from police codes to chemical counts, do not hold up.
The most widely accepted origin: the Waldos
The account with the most documentation behind it involves a handful of students at San Rafael High School, in Marin County, California, in 1971. They called themselves “the Waldos”, after the wall they used to sit on. Having heard about an abandoned cannabis crop nearby, they agreed to meet at 4:20 in the afternoon, after classes, to go looking for it. They never found it, but “4:20” stuck as a private code among them for cannabis itself.
The group has kept letters and other material from the period that support this version, which is one reason it is the one most researchers and journalists accept.
How a private joke went global
The spread came through music. Members of the group had connections with people around the Grateful Dead, and the term circulated in that scene through the 1970s and 1980s. In the early 1990s, a flyer handed out at a concert invited people to gather at 4:20 on 20 April, and a cannabis magazine picked it up and published it. From there the number became a code recognised far beyond California, and 20 April turned into an informal international day.
The myths that don’t hold up
- “It’s a police radio code.” There is no evidence of any police code 420 for cannabis.
- “There are 420 chemicals in cannabis.” The number of identified compounds is much higher and has nothing to do with the term.
- “It’s the best time of year to plant.” Planting seasons vary by region; the date has no agricultural origin.
- “It comes from a famous song or a historical date.” Coincidences have been attached to the number after the fact, not before.
Why the date feels odd in Europe
In the US, 20 April is written 4/20, so the number and the date line up naturally. In Spain and most of Europe the date is written 20/4, which is why the connection is less obvious here and why many Europeans learned the code as an imported piece of culture. The celebration still arrived: it sits in the spring calendar alongside events such as Spannabis, and it is part of the wider story we tell in a decade of cannabis culture in Barcelona.
Frequently asked questions
1. Why is 20 April a cannabis day?
Because in US date format it is 4/20, the number that became shorthand for cannabis culture.
2. Who invented 420?
The most documented account credits a group of students at San Rafael High School, California, in 1971.
3. Is 420 a police code?
No. That is one of the most repeated myths, and there is no evidence for it.
4. Is 420 celebrated in Spain?
It is known and marked within cannabis culture, though as an imported custom rather than a local one.
In short, 420 started as a meeting time for a group of California students and became, through music and magazines, the international shorthand for cannabis culture, with its own day on 20 April. Kush Weed Coffeeshop is a private association of adults on Carrer de Freixures, in the Santa Caterina area, with access restricted to registered members on prior application and identification. If you would like to know how the membership application works, get in touch and we will explain it.