What’s the origin of the phrase 420?

I never smoked pot until I was in my 40s, but I was aware of it all around me growing up in Southern California. “420” was a codeword, or a…

I never smoked pot until I was in my 40s, but I was aware of it all around me growing up in Southern California. “420” was a codeword, or a shortcut for all the culture that surrounded it. I thought I knew the origin of the phrase, based on stories I heard as a teen. But when I heard the Criminal podcast got the absolute true answer, I listened with glee, hoping to hear how right I was.

Episode 64: 420 (4.7.2017)
The Colorado Department of Transportation says the 420 mile markers on the state's highways were stolen so often, they…

Of course, I was wrong. So I asked people I knew what they thought the phrase/concept came from. All but one of them (an internet supernerd) were wrong too.

For the record, I had heard in college that it was from the San Diego-area school that Fast Times at Ridgemont High was based on, and it was the time everyone picked to go smoke a joint behind the school, which became shorthand for it. Most people I asked thought it was the police code for marijuana possession. Some thought it was hippies that concocted Earth Day in the 70s picking another day to celebrate pot.

After hearing “420” regularly for over 30 years, it was great to hear closure on the definitive history of the slang phrase. I won’t spoil it, it’s worth a listen.


I’m surprised this story has been a mystery to me for decades. I’m also surprised a podcast set out to answer it and instead of trying to weave an endless story of chasing the truth, they simply answer it definitively with proof in about 15 minutes.

It’s not everyday that you get absolute closure on a mystery from the 1970s.