The number 420 is associated with marijuana because it originated as a secret code used by a group of high school friends in San Rafael, California, in 1971. These friends, known as the Waldos, met at 4:20 p.m. to search for an abandoned cannabis crop based on a treasure map. They used "420" as a code for smoking marijuana. The term later spread through the Grateful Dead fan community and was popularized by High Times magazine in the 1990s. Since then, 420 has become a widely recognized number symbolizing marijuana culture, with April 20th (4/20 in the US date format) becoming an unofficial holiday for cannabis enthusiasts to celebrate and advocate for legalization.
