Happy 4/20! The True Story Behind Stoners' Favorite Number

Warren Haynes, the Allman Brothers Band guitarist, routinely plays with the surviving members of the Grateful Dead, now touring as The Dead. He's just finished a Dead show in Washington, D.C. and gets a pop quiz from the Huffington Post.

Where does 420 come from?

He pauses and thinks, hands on his side. "I don't know the real origin. I know myths and rumors," he says. "I'm really confused about the first time I heard it. It was like a police code for smoking in progress or something. What's the real story?"

Depending on who you ask, or their state of inebriation, there are as many varieties of answers as strains of medical bud in California. It's the number of active chemicals in marijuana. It's teatime in Holland. It has something to do with Hitler's birthday. It's those numbers in that Bob Dylan song multiplied.

The origin of the term 420, celebrated around the world by pot smokers every April 20th, has long been obscured by the clouded memories of the folks who made it a phenomenon.

The Huffington Post chased the term back to its roots and was able to find it in a lost patch of cannabis in a Point Reyes, California forest. Just as interesting as its origin, it turns out, is how it spread.

It starts with the Dead.

It was Christmas week in Oakland, 1990. Steven Bloom was wandering through The Lot - that timeless gathering of hippies that springs up in the parking lot before every Grateful Dead concert - when a Deadhead handed him a yellow flyer.