An informal observance on April 20 marking cannabis culture, its history, and the movement to reform cannabis laws.
Last updated March 18, 2026 · by the
Holiday Calendar Team
“Five San Rafael High School students coined '420' in 1971, and the slang spread through the Grateful Dead scene.
In 1971, five San Rafael High School students who called themselves the Waldos used '420' as a code while hunting for an abandoned cannabis crop. The term spread through the Grateful Dead scene and was carried to a national audience by High Times magazine in the 1990s.
The most repeated story about 420 is that it was a police radio code for someone smoking in public. It was not. Another says the number hides inside a Bob Dylan song, because 12 times 35 lands on 420. Dylan never confirmed it, and the math is a coincidence.
The real answer is smaller and stranger. In 1971, five teenagers in San Rafael, California set a meeting time and went looking for a cannabis patch they had been told was free for the taking. They never found it. The time stuck anyway.
Today April 20 is the calendar's unofficial cannabis day, observed worldwide. It is part celebration and part argument over law, in a country where the plant is legal in some states and still banned under federal rules.
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The group did not name itself after the plant. Five friends at San Rafael High School in Marin County called themselves the Waldos because they hung out at a wall outside the school. The cannabis came later, and almost by accident.
Their names are on the record: Steve Capper, Dave Reddix, Jeffrey Noel, Larry Schwartz, and Mark Gravich. In the fall of 1971 they heard about a treasure worth chasing.
A friend's brother in the Coast Guard was growing cannabis near Point Reyes and, the story goes, drew the Waldos a map and told them to harvest it. They agreed to meet and search after school.
The meeting point was a statue of the chemist Louis Pasteur on campus. The time was 4:20 PM, chosen for a dull reason: that was when sports and other activities tended to wrap up. They called the plan "4:20 Louie," then trimmed it to "420." The crop was never found, but the word outlasted the hunt.
One Waldo, Dave Reddix, took a job as a roadie for Grateful Dead bassist Phil Lesh in the early 1970s. The band's touring fans carried the slang from town to town.
It reached print by accident too. A Deadhead handed a flyer to a High Times reporter calling for a 4:20 smoke-out, and the magazine ran its first mention in May 1991. That early article wrongly tied the number to a police code, which is how the most stubborn myth about 420 began.
For years the Waldos were an unproven claim. Then they produced the receipts: postmarked letters from the 1970s and a copy of their 1974 high school newspaper, kept in a bank vault in San Francisco.
In 2017 the Oxford English Dictionary added "420" and cited those documents among the earliest recorded uses. By then the date had a second life as a reform rally, observed in a country still arguing over whether the plant should be legal at all.
TIMELINE
WHY THIS DAY MATTERS
A smoke-out became a standing argument over the law.
April 20 gatherings function as cannabis-law protests as much as celebrations, pressing for changes to local and national rules. Denver's Civic Center festival has drawn tens of thousands to make that case in public.
A code from one California schoolyard spread until April 20 became a shared marker across the United States, Canada, and beyond. Few pieces of teenage slang ever travel that far or anchor a calendar date worldwide.
The day lands inside a system where cannabis is legal for adults in many US states yet still banned under federal law. The contradiction is part of why the date carries weight beyond a party.
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It is an informal observance on April 20 tied to cannabis culture, its history, and the movement to reform cannabis laws. It is not an official or public holiday.
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