Weed enthusiast or not, chances are you probably associate April 20, or 4/20, with marijuana. But where did the stoner "holiday" originate? The two most common theories I heard growing up were because 420 was the police code [1] for Marijuana Smoking in Progress and that Adolf Hitler's birthday was on April 20. Though the latter is true, weed smokers don't gather to blaze in celebration of Hitler. Surprisingly (and I guess unsurprisingly), it all started with just a group of high school kids in Marin County, CA.
According to Time, the founding fathers of 4/20 were five male students [2] at San Rafael High School who would meet at 4:20 p.m. at a wall on campus to smoke together, giving them their name, the Waldos. Extracurricular activities were usually over by this time, which led them to use 420 as code for marijuana within their group. One of the members, Dave Reddix, scored a job as a roadie for the band the Grateful Dead, who helped blow out the phrase. A group of fans in Oakland passed out flyers on Dec. 28, 1990, inviting people to smoke 420 on April 20 at 4:20 p.m. Steve Bloom, former reporter for High Times, got his hand on one of these and the magazine ended up printing the flyer in 1991 and kept the reference alive.
Since then, 420 has integrated into mainstream culture and is celebrated each year at the exact same time by people who unite to smoke out. One well-known tradition includes 4/20 at Hippie Hill [4] at San Francisco's Golden Gate Park (pictured above), where over 8,000 people gathered in 2016 [5]. Bet the Waldos didn't expect their inside code to grow into what it is today. Happy smoking!