In the 1970’s, “420” was the codeword that a group of high school friends used for smoking weed. Through a family connection, one of them became a roadie for the Grateful Dead, who picked up the term. Their fans, known as Deadheads, started using the term as well and it became a tradition to smoke weed at 4:20pm. In 1990, a group of Bay Area Deadheads decided to gather on April 20th the next year to smoke weed together at a local hiking viewpoint. High Times magazine caught wind of it and spread the word. From there it became a national pothead holiday.