A cannabis cola with the text "Where did "420" come from?"

You needn’t be a big smoker to know that April 20 (4/20) is an international holiday. But few know how the number 420 became synonymous with recreational THC-cannabis use, or who popularized the date April 20th as the “marijuana holiday.”

Where Did ‘420’ Come From?

There are many folk tales about how 420 gained its significance, like:

  • It refers to the number of chemical compounds (cannabinoids) found in the cannabis plant.

  • If you take the Bob Dylan song “Rainy Day Women #12 & 35” and multiply the numbers, you get 420.

  • The number comes from the U.S. House Bill to legalize THC cannabis.

  • It’s the code among police officers to refer to “marijuana smoking in progress.”

  • It’s named for the day Bob Marley died (he passed on May 11th)

  • April 20th is the best time of year to plant your cannabis (This may be true, depending on your climate)

The History of ‘420’

The most believable story takes us back to San Rafael, California in 1971. It was here, in a small Bay area city, where a group of high school friends, lovingly named “Waldos” for their affinity for leaning on walls, started smoking cannabis.

Nixon’s War on Drugs started the same year as a means to control organized youth movements and political opponents of the Vietnam War. Cannabis, a favorite among the coming-of-age baby boomer generation became the top target.

The Waldos needed some way to communicate with one another about their after-school intentions. “4:20 Louis” meant ‘meet at the campus’s statue of Louis Pasteur after class.

One Waldo is quoted in the San Francisco Chronicle as saying “[420] was just a joke, but it came to mean all kinds of things, like, ‘Do you have any?’ or ‘Do I look stoned?”

How ‘420’ Went Mainstream

One of the Waldos, Dave Reddix, would go on to work with the Grateful Dead’s Phil Lesh as a roadie. The band is believed to help popularize ‘420’ among its audiences, even going so far in 1990, as to hand out flyers that invited fans to smoke ‘420’ on April 20 at 4:20 ᴘ.ᴍ.

As Deadheads traveled, so too did ‘420.’ A year after the flyer in 1990, a reporter for High Times Magazine printed the invitation and the number picked up steam, continuing to grow over the last 30 years.