The Story Behind 420

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Dr Weedy Team

Chromometer 3 min

Have you ever wondered why and how the prime numbers 4-2-0 became associated with cannabis? Was it just a spontaneous coincidence or was it someone’s secret plan?


As with any good mystery, this story has several versions:

  1. Some say “420” is code among police officers for “marijuana smoking in progress”. Well, we’ve checked, but there’s no evidence to support those claims. Section 420 of the California penal code refers to obstructing entry on public land. The penal codes of other states list different entries for 420, but none of them matches anything having to do with marijuana.
  2. Others note 4/20 is Adolf Hitler’s birthday. Yes, but don’t search for a connection where there isn’t one. Although there is documentary evidence that the Fuhrer regularly abused multiple substances, weed was not among them.
  3. Some go as far as to cite Bob Dylan’s song “Rainy Day Women #12 & 35” because 12 multiplied by 35 equals 420. These are good mathematical calculations, but no more.
  4. Another theory is that there are 420 active chemicals in marijuana, hence an obvious connection between the drug and the number. But that’s not quite true either, with nearly 500 such components in marijuana.
  5. A lesser-known possibility comes from the 1939 short story “In the Walls of Eryx” by H.P. Lovecraft and Kenneth Sterling. The story describes “curious mirage-plants” that seemed fairly similar to marijuana and appeared to get the narrator high at around 4:20. Since the story is from 1939, it’s perhaps the earliest written link between marijuana and 420.
  6. The most credible story traces 4/20 to Marin County, Calif. The tradition started in 1971 when five students from San Rafael High School would meet at 4:20 p.m. by the campus’ statue of chemist Louis Pasteur to partake. They chose that specific time because extracurricular activities had usually ended by then. This group became known as the “Waldos” because they met at a wall. They would say “420” to each other as code for marijuana. The ritual spread, and soon 420 became code for smoking marijuana. Eventually 420 was converted into 4/20 for calendar purposes, and the day of celebration was born.

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