Why Is 4/20 “Weed Day”? The Internet Has Some Interesting Theories

No, it's not Bob Marley's birthday.


Practically every lover (and non-lover) of marijuana knows that April 20 is an international holiday to indulge in the drug. However, if asked what the origin of 4/20 is, it’s unlikely most would know the holiday’s purported origin story — in part because there are a few.

As it turns out, there are countless theories out there as to why “Weed Day” falls on April 20 every year. Inverse has rounded up some of the best of these, along with one that’s probably the real deal.

The Birth or Death of Bob Marley

Despite this theory being logically disproved over and over again, many believe 4/20 refers to either the life or death of reggae artist and weed culture icon Bob Marley. In fact, while Marley may have celebrated 4/20 himself, he was born on February 6, 1945. The late musician died on May 11, 1981, quite a few weeks after April 20, so this theory is most definitely out.


California’s 420 Penal Code

Legend has it that 4/20 refers to California’s criminal code that once outlawed the sale and distribution of the recreational drug. But even before it became a cannabis haven, California’s 420 state code actually referred to to obstructing entry on public land.

A Bob Dylan Song

Another interesting theory is this mathematical reference in one of Bob Dylan’s songs. “Rainy Day Women #12 & 35” from the crooner’s 1966 album Blonde on Blonde, in which listeners are meant to do some multiplication to arrive at “420.” Yes, 12 times 35 does equal 420, and the song does contain the lyrics, “Everybody must get stoned.”

420 Chemicals in Marijuana

This theory has been straight debunked, thanks to science. Studies have shown that many marijuana strains contain more than 500 compounds, depending on the strain.

The Legend of the Waldos and the Grateful Dead

Perhaps the most well-known and most plausible 4/20 theory, the “Waldos” legend is based on a group of 1970s California students at San Rafael High School. Naming themselves after the term coined by Buddy Hackett, which describes “odd people,” the teen clique concocted a tradition of meeting at 4:20 p.m. to smoke after school. Their website states that this particular time was a perfect way to remember the pre-scheduled ritual.

Subsequently, the group used the term “420” to reference any time they wanted to get high from grade school onwards. The code remained used on the hush for the next decade or so until the group began hanging backstage at Grateful Dead concerts — apparently, Reddix’s older brother was a pal of bassist Phil Lesh. The band and their crew picked up the colloquialism, and the story also goes that during late 80’s gigs, “420” flyers describing the code as a weed culture password of sorts began to circulate among show-goers. This is also where the confusion between the Waldos’ 420 code and the California penal code theories is said to originate from, as the flyers apparently dictated that 420 was also police code for smoking marijuana.

Little did the Waldos know that their private lexicon would become a treasured holiday for weed culture and its community. “We thought it was a joke then,” one of those students, David Reddix, told NBC News of the ritual. “We still do.”