Where 420 came from: the Waldos
Britannica calls it the most commonly accepted explanation: in 1971, a group of high school students in San Rafael, California, met regularly at 4:20 to search for an abandoned cannabis crop.
The details come from the students themselves. According to an Associated Press report, 5 friends (Dave Reddix, Steve Capper, Larry Schwartz, Jeff Noel and Mark Gravich) hung out at a wall at San Rafael High School and called themselves the Waldos. In the fall of 1971, a classmate brought them a hand-drawn map of a cannabis patch in Point Reyes National Seashore that his brother-in-law, a Coast Guard reservist, was giving up. The friends agreed to meet at the school's statue of Louis Pasteur at 4:20 p.m., when 2 of them finished football practice.
They never found the patch. "420 Louis" became their hallway signal for another search, then got shortened to 420, meaning let's get high anywhere. Time reports they picked 4:20 because after-school activities had usually ended by then.
Another San Rafael group, led by a man known as The Bebe, has claimed it coined the term a year earlier, but CBC reports that most agree the Waldos made the stronger case, backed by evidence. In 2018, the AP reported that the Oxford English Dictionary had added 420 the year before after reviewing the Waldos' records, and credits them as its creators.
How a school code went worldwide
The code stayed in the Waldos' circle until they started hanging out backstage at Grateful Dead concerts. Reddix's older brother was friends with bassist Phil Lesh, the AP reported, and Time says Reddix later worked for Lesh as a roadie. The band's crew picked up the slang.
On December 28, 1990, Deadheads in Oakland handed out flyers inviting people to smoke 420 on April 20 at 4:20 p.m. One reached Steve Bloom, a reporter at High Times. The magazine printed the flyer in 1991 and kept using the number, and in 1998 it acknowledged the Waldos as the inventors, according to Time.
Bloom later credited the flyer's authors with the idea of a yearly day for smoking together: "They birthed the idea of a stoner holiday, which April 20 has become." The date works because 4/20 is the US way of writing April 20, as Wikipedia notes. For more of the vocabulary, see the cannabis slang guide and the story of the cannabis leaf symbol.
420 myths that are false
Plenty of origin stories have circulated. These do not hold up:
- It is a police code. False. Britannica calls the idea that 420 is New York or Los Angeles police code for marijuana an urban legend, and CBC lists the California penal code among the things 4/20 has no connection to. Flyers handed out at Grateful Dead shows helped spread this one: the AP reported they claimed 420 was California police code for marijuana smoking in progress, which it is not.
- Cannabis contains exactly 420 chemicals. False. Britannica puts the figure at some 480 chemicals, and a 2021 review in the journal Molecules says more than 500 compounds have been reported from the plant.
- It comes from a Bob Dylan song. "Rainy Day Women #12 & 35" multiplies out to 420 (12 times 35), but Time lists it among the false explanations. Britannica adds that Dylan denied the song was about cannabis.
- It marks a historical event on April 20. April 20 is Adolf Hitler's birthday, and CBC points out other events that share the date, but none of them has anything to do with 420. CBC also rules out links to Bob Marley's death and to Willie Nelson.
4/20 in Canada
Canadian 4/20 gatherings have long mixed celebration with protest. Non-medical cannabis has been legal for adults since October 17, 2018, according to the Government of Canada, and the events have shifted since.
- Vancouver: after construction displaced the rally from the Vancouver Art Gallery plaza, it moved to Sunset Beach, where police estimated about 35,000 people in its second year there, CBC reported; the head organizer called it a protest at its core. In 2026, CTV News described a smaller, more subdued crowd at the Vancouver Art Gallery, at an event that used to draw thousands.
- Ottawa: the gathering is on Parliament Hill. At one Hill smoke-in, CBC reported an RCMP estimate of 5,000 to 6,000 people, a crowd that had first met at nearby Major's Hill Park. In 2019, the first 4/20 after legalization, rain kept the crowd to about 1,000 at the 4:20 countdown, with about 3,000 coming and going by an organizer's estimate, The Canadian Press reported.
- Toronto: the same 2019 Canadian Press report described a gathering at Woodbine Park in the east end, where a dispensary owner said the mood felt more celebratory than past 4/20s, which had felt more like protests.
Does 4/20 mean more car crashes?
A 2018 study in JAMA Internal Medicine by researchers at the University of British Columbia and the University of Toronto looked at 25 years of US crash data and found a 12% higher relative risk of fatal crashes after 4:20 p.m. on April 20 than on comparison days a week before and after. When McGill University epidemiologists Sam Harper and Adam Palayew compared 4/20 with more days, they found very little evidence of extra risk, Scientific American reported.
What is not in doubt is the impairment. THC affects reaction time and coordination, and Health Canada says impairment can last more than 24 hours. Canada's lower-risk guidelines say not to drive for at least 6 hours after using cannabis. If you are marking the day, sort out your ride home first, and see how to smoke weed with lower risk.
Marking 4/20 in Toronto
If you are stocking up, GasDank delivers same day across Toronto and the GTA, usually within 1 to 2 hours, and ships mail order across Canada. GasDank sometimes runs $40 ounce specials, listed on the deals page; regular ounces start from $50, and you can browse flower online. Customers must be 19 or older (21 in Quebec), with ID checked at the door.
