Both marijuana smokers and non-smokers recognize April 20 or 4/20 as a national holiday in United States for cannabis culture, but few actually know how the date got chosen.

The stoner’s code “420” has been around since the early 1970’s and is used for an array of slang, but do you know where it came from?

It is probably hard to find a marijuana user who does not consider 420 to be a sacred time and date. But it is certainly more difficult to find anyone who has a certain answer of what 420 means and where its use originated. Sure there are plenty of people who are positive that they know this information, but if you ask 5 people the same question, you are likely to get 5 different 100% positive responses—there are just too many 420 truths floating around.

Some say “420” is code among police officers for “marijuana smoking in progress.” Some note 4/20 is also Adolf Hitler’s birthday. And some go as far as to cite Bob Dylan’s song “Rainy Day Women #12 & 35” because 12 multiplied by 35 equals 420.

But, to put it bluntly, those rumors of the history behind how April 20, and 4/20, got associated with marijuana are false.

The Waldo’s

The most credible story traces 4/20 to Marin County, Calif. In 1971, five students at 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 — Steve Capper, Dave Reddix, Jeffrey Noel, Larry Schwartz, and Mark Gravich — became known as the “Waldos” because they met at a wall. They would say “420” to each other as code for marijuana.

The Waldo’s heard of a marijuana crop that was hidden in the nearby San Reyes peninsula and they agreed to meet at a statue of Louis Pasteur near the school to seek out the buds. The group would meet week after week in the same spot at the same time, they would pile into their car and smoke joint after joint on their way to search for the mystical marijuana crop.

Originally, the group would say “420-Louis” as their code as their code to schedule a meeting. Eventually, they dropped the “Louis” because they found themselves using the term “420” to describe anything marijuana related.

Grateful Dead

The Waldo’s may have connected 420 and marijuana in their high school days, but it was the Grateful Dead that helped it catch on in American counterculture. After the Haight-Ashbury scene was overrun with “speed freaks”, “thugs” and “artists”, the Grateful Dead packed up and headed to Marin County hills, just a few blocks from

After the Haight-Ashbury scene was overrun with “speed freaks”, “thugs” and “artists”, the Grateful Dead packed up and headed to Marin County hills, just a few blocks from the Waldo’s high school.

Mark Gravitch, another original Waldo, recalled that his father managed real estate for the Dead, so the group often knew where the band would be. Dave Reddix’s (also an original Waldo) brother managed a Grateful Dead cover band and was friends with Phil Lesh, the band’s bassist.

The Waldo’s remembered often hanging outside of the band’s rehearsals, they would smoke joints and listen to the band practice.

The Waldo’s managed to get the term 420 stuck in the band member’s heads and as they began using it 420 was solidified in history. The group was often invited to Dead parties and they would use the term in those crowds, further spreading the popularity of 420.

Phil Lesh admitted that Dave Reddix is an old friend of his and that it is likely that he and his friends coined the term, adding to the validity of the Waldo’s claim to fame.

High Times eventually picked up the term, in the early 90’s, and published it throughout their magazine. Many believe this is how/when the term went global.

Today we use 420 less as a code and more as a celebratory roar. Everyone knows that 420 signifies something to do with marijuana and I doubt that will ever change.

Treat yourself to some new 420 gear, like the Mighty Vaporizer, at the Herb Shop.

As Reddix told TIME in 2017, “We got tired of the Friday-night football scene with all of the jocks. We were the guys sitting under the stands smoking a doobie, wondering what we were doing there.”

The shenanigans continued long after 4:20 p.m., too. The group challenged each other to find ever-more-interesting things to do under the influence, calling their adventures “safaris.”

Later, Reddix’s brother helped him get work with Grateful Dead bassist Phil Lesh as a roadie, so the band is said to have helped popularize the term “420.” On Dec. 28, 1990, a group of Deadheads in Oakland handed out flyers that invited people to smoke “420” on April 20 at 4:20 p.m. One ended up with Steve Bloom, a former reporter for High Times magazine, an authority on cannabis culture. The magazine printed the flyer in 1991 and continued to reference the number. Soon, it became known worldwide as code for marijuana. In 1998, the outlet acknowledged that the “Waldos” were the “inventors” of 420.

Bloom, now the publisher of Celebstoner.com, has credited the people who wrote the flyer for the date’s reputation as an annual gathering of pot smokers. “They wanted people all over the world to get together on one day each year and collectively smoke pot at the same time,” he wrote in 2015. “They birthed the idea of a stoner holiday, which April 20 has become.”

With inputs from Time and Herb.co.

Photo Credit: Time, The Himalayan Times, Archaic Nepal and Herb.co