4/20: How Ordinary Numbers Became the Code for “Time to Smoke Weed”

The term “4/20” has evolved from a simple date into a widely recognized cultural code associated with cannabis consumption, particularly the time 4:20 p.m. As a moment to smoke marijuana.

This association originated in the early 1970s among a group of high school students in San Rafael, California, known as the “Waldos,” who would meet at 4:20 p.m. To search for an abandoned cannabis crop. Though their search was unsuccessful, the time became a ritual and later spread through connections with the Grateful Dead and countercultural networks.

Over time, “420” entered mainstream usage as a discreet reference to marijuana use, appearing in music, film, and internet culture. By the 1990s, it was embraced by cannabis advocacy groups and eventually became a symbol for annual celebrations on April 20th, with events held in cities around the world advocating for legalization, and reform.

The cultural penetration of “4/20” is evident in its adoption beyond cannabis circles, sometimes used generically to mark a break or leisure moment, though its primary association remains tied to marijuana consumption. Despite its informal origins, the term has shown remarkable durability and adaptability across decades and regions.

While the precise mechanics of how the term spread are still discussed, multiple accounts confirm its roots in California youth culture and its organic growth through music and counterculture channels. No single individual or organization claims ownership, but the narrative of the Waldos is widely cited in reputable sources as the origin point.

Today, April 20th is observed globally not only as a countercultural holiday but also as a day for public discourse on cannabis policy, with demonstrations, educational events, and festivals occurring in countries where legalization efforts are underway or have succeeded.

The persistence of “4/20” illustrates how informal, grassroots practices can evolve into enduring cultural symbols, shaped by repetition, shared understanding, and media amplification over time.