What is 420? It's cannabis culture's shorthand for cannabis itself, and April 20, or 4/20, is its unofficial holiday. The number traces back to a group of friends in San Rafael, California, who used 4:20 as a meeting time in 1971. Here's the real story, the myths to skip, and how adults 21 and older can mark the day legally in Michigan.
What Is 420? The 1971 Origin Story
In the fall of 1971, five friends at a San Rafael, California, high school, nicknamed the Waldos after the wall where they hung out, heard about an abandoned cannabis patch near Point Reyes. They agreed to meet at a Louis Pasteur statue at 4:20 p.m., after practice, to go look for it. They never found the plants, but "4:20" stuck as their code word. The group has kept postmarked letters from the 1970s that use the term.
How the Code Spread
The Waldos had ties to the Grateful Dead's circle, and the slang traveled through the band's crew and fans. During Christmas week of 1990, a magazine reporter at a Dead show in Oakland was handed a flyer inviting people to meet "at 4:20 on 4/20 for 420-ing in Marin County." His cannabis magazine picked up the story and helped carry the term worldwide.
Myths That Don't Hold Up
You may hear that 420 is a police radio code, the number of chemical compounds in cannabis, a famous birthday or the math behind a Bob Dylan song title. The Waldos themselves reject the police-code story, and none of the other theories comes with the dated paper trail their letters provide.
From Counterculture Code to Retail Calendar
Over the decades, 4/20 grew from an inside joke into a day of rallies and gatherings. As states legalized, many retailers began marking it with promotions. In Michigan, voters approved adult-use cannabis in 2018, and the law took effect that December.
Michigan's Own Spring Tradition
Michigan has a spring cannabis tradition that predates legal sales by decades. Ann Arbor's Hash Bash has run every year since 1972 and now falls on the first Saturday in April; the 2026 rally was April 4. It grew out of the protests over poet John Sinclair's 10-year sentence for possessing two joints. Today it's part rally, part reunion. Even at a rally, Michigan law doesn't allow consuming cannabis in public.
Celebrating Legally in Michigan
- Celebrate on private property where it's allowed; using cannabis in public places isn't.
- You must be 21 or older, and never share with anyone under 21.
- Don't use cannabis while driving or drive under the influence. Plan rides ahead.
- Keep it in Michigan: don't travel across state lines with cannabis, even into another legal state.
Our Michigan cannabis law guide covers possession limits and the rest.
A Home-Cooked 4/20
Cooking at home is a low-key way to mark the day. Infused butter and oil are the base of most recipes, and our guides to cannabutter and cannabis oil walk you through both. Homemade potency is always an estimate: it depends on your starting flower, how well it was decarboxylated and how much was lost during infusion. Start with a small serving, wait at least two hours before having more, and label anything infused and keep it away from kids and pets.
Shopping Ahead
If you're stocking up, browse your store's menu and order ahead for in-store or curbside pickup to keep your visit quick. Check our deals page for current offers and our 4/20 shopping guide for more tips. New to edibles? Start low.
