420, 4:20, or 4/20 (pronounced four-twenty) is a code-term that refers to the consumption of Cannabis and by extension, as a way to identify oneself with cannabis subculture or simply cannabis itself. Observances based on the number 420 include smoking cannabis around the time 4:20 p.m. (with some sources also indicating 4:20 a.m) on any given day, as well as smoking and celebrating cannabis on the date April 20 (4/20 in U.S. form).
A group of teenagers in San Rafael, California, calling themselves the Waldos because "their chosen hang-out spot was a wall outside the school", used the term in connection with a fall 1971 plan to search for an abandoned cannabis crop that they had learned about. The Waldos designated the Louis Pasteur statue on the grounds of San Rafael High School as their meeting place, and 4:20 p.m. as their meeting time. The Waldos referred to this plan with the phrase "4:20 Louis". Multiple failed attempts to find the crop eventually shortened their phrase to simply "4:20", which ultimately evolved into a codeword that the teens used to mean marijuana-smoking in general. Mike Edison says that Steve Hager of High Times was responsible for taking the story about the Waldos to "mind-boggling, cult like extremes" and "suppressing" all other stories about the origin of the term.
Hager wrote "Stoner Smart or Stoner Stupid?" in which he called for 4:20 p.m. to be the socially accepted hour of the day to consume cannabis. He attributes the early spread of the phrase to Grateful Dead followers, who were also linked to the city of San Rafael.
April 20 observances
April 20 has become a counterculture holiday in North America, where people gather to celebrate and consume cannabis. Some events have a political nature to them, advocating for the legalization of cannabis. North American observances have been held in San Francisco's Golden Gate Park near the Haight-Ashbury district, the University of Colorado's Boulder campus, Ottawa, Ontario, at Parliament Hill and Major's Hill Park, Montréal, Québec at Mount Royal monument, Edmonton, Alberta at the Alberta Legislature Building, as well as Vancouver, British Columbia at the Vancouver Art Gallery. The growing size of the unofficial event at UC Santa Cruz caused the Vice Chancellor of Student Affairs to send an e-mail to parents in 2009 stating: "The growth in scale of this activity has become a concern for both the university and surrounding community."
Events have also occurred in Auckland, New Zealand at the Daktory[unreliable source?] and Dunedin, New Zealand, at University of Otago.
In Colorado, the Colorado Department of Transportation replaced the frequently stolen Mile Marker 420 sign on I-70 east of Denver with one reading 419.99 in an attempt to stop the thievery.
Legality of cannabis by country Entheogenic use of cannabis