The number 420 is the world's most recognised cannabis code. Its true origin — five California teenagers meeting at 4:20pm in 1971 — is documented. Here is the complete story of how a time became a culture.
The true origin of 420 is documented and traceable to five students at San Rafael High School in California in 1971. The group, who called themselves the Waldos because they hung out by a wall outside school, received a hand-drawn map from a friend whose brother had planted a cannabis crop near Point Reyes and could not tend it. The Waldos agreed to meet at the Louis Pasteur statue outside their school at 4:20pm to begin the search. The plan was: 4:20 at Louis. They repeated the expedition multiple times, never finding the crop, but the phrase 420 Louis became abbreviated to simply 420 as a code word for meeting to smoke cannabis. The Waldos have provided corroborating documentation including a 1971 letter using the term, a 1974 wall flag using it, and contemporaneous accounts from identifiable individuals, satisfying journalist and historian standards for confirming the claim. They were connected to the Grateful Dead through personal friendships — Waldo Steve was working for the Grateful Dead band and Waldo Dave’s older brother managed the Dead-affiliated Grateful Dead bassist Phil Lesh’s band — which is how the term moved from a private San Rafael code to the wider Dead subculture. Connect this story to the broader counterculture history.
The Grateful Dead and their community of followers (Deadheads) were one of the most networked cannabis-using subcultures in America through the 1970s and 1980s. The Waldos had direct access to Dead social circles and the term 420 spread through Deadhead culture through informal use at concerts and gatherings. A 1990 flyer distributed at a Grateful Dead concert invited people to smoke 420 on April 20th at 4:20pm — the first known written connection between the number and the date as a cultural event. This flyer was picked up by Steven Hager at High Times magazine, who published a story about 420 in 1991. The High Times platform, with international circulation among cannabis enthusiasts, spread the term to audiences far beyond the Grateful Dead orbit. By the mid-1990s, 420 was used internationally as cannabis code. By the 2000s, April 20 was an informal cannabis holiday in multiple countries. The High Times magazine history explains how the publication served as cultural infrastructure for cannabis community.
April 20 (4/20 in American month-day notation) became a global cannabis cultural event through the 1990s and 2000s. Gatherings at 4:20pm on April 20 occurred at universities, parks and public spaces across North America and Europe. The San Francisco Bay Area, with its historical connection to both the Waldos and Grateful Dead culture, hosted the largest annual gathering at Hippie Hill in Golden Gate Park. These gatherings were informal, non-organised, and explicitly cannabis-friendly at a time when cannabis remained illegal across most of the US. They functioned as highly visible acts of collective civil disobedience that demonstrated the scale of cannabis use and the impossibility of enforcement. After Colorado and Washington legalised recreational cannabis in 2012, the first legal 420 gatherings at Denver’s Civic Center Park in 2013 attracted over 80,000 people. Cannabis brands, dispensaries, and media have since turned April 20 into a commercial holiday with 420 sales, events and product launches.
Multiple false origin stories for 420 have circulated widely. The most persistent: that 420 refers to the number of active chemical compounds in cannabis (false — approximately 500 compounds are now identified), that it references California Penal Code 420 (false — that code addresses obstruction of entry to public land, not cannabis), that police radio code 420 means marijuana use in progress (false — varies by jurisdiction and most use no such code), and that it derives from Bob Dylan’s Mr. Tambourine Man because the song contains 12 choruses of 8 bars at 60 BPM giving 5.76 minutes, which multiplied by some factor gives 420 (false and mathematically tortured). The false origins spread because they sounded plausible before the Waldos’ documented account became widely known. The persistence of false origin stories is itself culturally interesting: 420 filled a cultural need for a cannabis code before it had an explained origin, and the mystery was part of its appeal. Explore High Times magazine which debunked many of these myths officially.
The Waldos — five students at San Rafael High School in California — coined 420 in 1971 as a code for meeting to smoke cannabis at 4:20pm. The term spread through their connection to Grateful Dead culture and was amplified by High Times magazine in 1991.
April 20 (4/20 in American date format) became cannabis culture's informal holiday because 420 was already established as a cannabis code. A 1990 Grateful Dead concert flyer specifically proposed smoking at 4:20pm on April 20, and the date became standardised as the annual cannabis cultural gathering day.
No. This is a persistent myth. No major US police jurisdiction uses radio code 420 to mean cannabis. The Waldos' documented San Rafael High School origin is the confirmed true story.
Steve Hager at High Times magazine encountered 420 through the Grateful Dead community and published a story about it in 1991. The magazine's international circulation among cannabis enthusiasts spread the term globally. High Times subsequently hosted 420 events and incorporated the term throughout its editorial identity.
420 events range from informal gatherings in parks at 4:20pm on April 20 to large organised festivals with live music, vendor markets and cannabis consumption in legal jurisdictions. Denver's Civic Center Park hosts one of the world's largest, with 80,000+ attendees in legal years. Cannabis brands use 420 for major annual promotions and product launches.