CHICAGO (NewsNation) — Cannabis smokers across the globe are celebrating marijuana use Thursday as it marks the annual event otherwise known as 420.

Every year on April 20, pot users gather to smoke the herb and campaign for the popular drug to become legalized in parts of the world where it is prohibited, according to The Independent.

While marijuana is illegal at the federal level in the U.S., nearly half of the states have legalized recreational marijuana use, and even more have legalized the drug for medicinal purposes.

Just in the past six months, Rhode Island, New York and Connecticut have all kicked off legal sales, and Maryland is preparing to allow adult use starting on July 1.

However, weed remains entirely illegal in only three states: Idaho, Kansas and Nebraska, according to the National Council of State Legislatures. 

The rehabilitation of marijuana in public opinion began around 1996, when California became the first state to legalize cannabis for medical use. Societal support for legal marijuana doubled from 25 percent in 1995 to 50 percent in 2011, just before the debut of recreational cannabis. The last Gallup survey, in 2022, found 68 percent of Americans supporting legal marijuana. 

Now, the term 420 has become a popular vernacular among Americans.

But, according to popular lore, the origin of 420 began with a group of California high schoolers in the early 1970s. A group of Northern California’s San Rafael High School students, who dubbed themselves the “Waldos,” used to gather at 4:20 p.m. to smoke weed together, USA Today reported.

An original Waldo, Steve Capper, told USA Today that they weren’t “stupid stoners” though, explaining that the group was made up of exceptional students who engaged in after-school activities. They chose the time 4:20 p.m. because it was the only time that the group could meet up between sports practices and study groups, Capper said.

Capper was joined by four other students: Dave Reddix, Jeffrey Noel, Larry Schwartz and Mark Gravich, according to their website. The group came up with the term ‘420’ as a secret term to communicate they would gather later that day to smoke, a Daily Mail report said.

The Waldos even documented their proof that they were the earliest “known” group that used the term on their website. The group’s multiple pieces of physical evidence that they used the term have been preserved in a high-security bank safety deposit vault” in a San Francisco bank, according to the 420Waldos website.

NewsNation affiliate KDVR and The Hill contributed to this report.