The fall harvest was approaching nearly 50 years ago with some mature flower ready to bud near the Point Reyes Coast Guard station in California, about 30 miles northwest of San Diego.

As the story goes, a group of five high schoolers from nearby San Rafael got wind of a service member who could no longer tend his plot of cannabis plants somewhere in the forest not too far from the station, where a Coast Guard communications facility would be commissioned the following year in 1972.

Dubbed the Waldos by virtue of their favorite hangout spot—a wall outside their school—the five friends would meet once a week at 4:20 p.m. after their athletic practices, according to History.com. Their motive? To conduct a search for the abandoned cannabis plants with a treasure map in hand.

One of the original Waldos, Steve Capper told the Huffington Post of the tale in 2010.

“We’d meet at 4:20 and get in my old ‘66 Chevy Impala and, of course, we’d smoke instantly and smoke all the way out to Point Reyes and smoke the entire time we were out there. We did it week after week,” Capper said. “We never actually found the patch.”

While many 420 revelers across the nation and throughout the world now celebrate April 20 as an unofficial holiday for cannabis, the origins of the phrase still escape some, who entertain various theories, such as Adolf Hitler’s birthday (April 20, 1889); 4:20 p.m. being teatime in Holland or the last smoke break of the workday; the myth that 420 is the number of active compounds in cannabis; or even a multiplication code from Bob Dylan’s 1966 hit “Rainy Day Woman Nos. 12 and 35.”

A more accepted origin, 420’s roots go back to the Waldos, who began coining the phrase as a code word for cannabis. But it wasn’t until the Grateful Dead came to town that their cannabis culture slang term began its path toward a household expression internationally. Beginning in the late-1960s, the Dead called the hills of Marin County its home, just blocks away from San Rafael High School.

According to the Huffington Post, Waldo Mark Gravitch’s father managed the Dead’s real estate, while fellow Waldo Dave Reddix’s older brother, Patrick Reddix, was friends with Dead bassist Phil Lesh. Through those connections, the Waldos, also including Jeffrey Noel and Larry Schwartz, had open access to Dead gatherings and rehearsals, where their 420 slang became a catchphrase throughout their community and then spread further during the Dead’s tours.

When former High Times editor Steve Hager, who was hired at the magazine in 1988, starting using the term in print, 420 emerged from the Dead underground and never turned back.

While many revelers still have their own versions of 420’s origins, evidence of the term prior to the Waldos’ 1971 use remains to be seen. The Waldos still have their original 420 tie-dyed flag from high school, a newspaper clipping where one of the members discusses wanting to say “420” for his graduation speech and postmarked letters among the group filled with 420 references, according to History.com.

Next Tuesday, nearly 50 years after the Waldos started using the term, a growing number of state-legal businesses can now celebrate the cultural significance of 420 through featured retail product specials, vendors, live entertainment and more, as public acceptance of cannabis continues to spread.

-Tony Lange, Associate Editor