Code 420: The Story Behind American Cannabis Culture's Favorite Number (3 photos)
In American cannabis culture, the number 420 holds a special place. It pops up constantly in lyrics, media, and everyday conversations about weed—and dropping "420" into casual chat is often a discreet invitation to smoke up. T-shirts, caps, belts, and backpacks stamped with the number signal that the owner is in the know. But where did this secret code actually come from? 
In the U.S., "420" refers to either 4:20 p.m.—the traditional time to smoke cannabis—or April 20 (4/20 in the American date format). The day serves as an informal holiday for cannabis culture, where people gather for community events, rallies, and demonstrations calling for legalization. 
Why 4:20? As it turns out, the tradition dates back to 1971 in San Rafael, California, among students at San Rafael High School. The group agreed to meet at 4:20 p.m.—right after their last class—by a statue of Louis Pasteur to smoke. Initially, their shorthand was "420 Louis!" As the slang caught on and spread wider, it was eventually shortened to just "420."
Thus, 4:20 p.m. became the cannabis counterpart to traditional British afternoon tea. April 20 became the unofficial "Weed Day" much later, riding the wave of growing pro-legalization movements. In parts of the U.S., the date coincides with Earth Week, giving it what many fans see as a special, almost sacred resonance. 
The code number "420" frequently pops up in rap lyrics and American movies, though it easily slips by those unfamiliar with the reference. For instance, have you ever noticed that in Quentin Tarantino's cult classic
Pulp Fiction
, nearly every clock on screen is set to 4:20?
