Why does America try to get high on April 20, ideally at 16:20 hours? Everyone knows the answer. April 20 can be written 4/20, and 16:20 hours is 4:20 p.m. We wait only for a future U.S. Congress to officially declare 420 National Pot Smoking Day. But how did this time and date get permanently inscribed in the minds of stoners? Holiday, as we all know, comes from “holy day.” In parts of the world, St. Patrick's Day still has strong religious connotations related to Ireland's patron saint. In others, it is solely dedicated to the veneration of leprechauns and alcohol.

The new holiday of 420 may be secular, but like St. Patrick's Day, featuring drinks ranging from Guinness to Irish Car Bombs, 420 has its own sacrament, the wacky weed. Just as it's always 5 p.m. somewhere in the world, as the drinkers among us rationalize, any time of the day can be 420, the perfect moment to wake and bake.

In Los Angeles, it sometimes seems that the majority of dispensaries, delivery services, recommendation-granting doctor's offices, cannabis-finder websites, hydroponics outlets and other parts of the marijuana ecosystem are packed with 420 references. Phrases such as “420-friendly” appear in roommate ads on Craigslist, indicating that the occupants are officially licensed medical marijuana recipients and probably won't freak out over bong-water spills.

Indeed, a recent Google search for “420” brought up 913 million hits. But where did “420” actually come from?

The Huffington Post asked Warren Haynes, an Allman Brothers Band guitarist who also plays with the current Grateful Dead, where the term “420” comes from. “I don't know the real origin. I know myths and rumors,” he says. “The first time I heard it?…?it was like a police code for 'smoking in progress,' or something. What's the real story?”

Haynes put his finger on it. There are a lot of crazy stories about the origins of 420. Let us clear it up for you:

Q: Does 420 commemorate the death of Bob Marley?

A: No. It is not the date Bob Marley died (he died on 5/11/81), nor is 4/20 his birthday. It is also not the date that Jimi Hendrix, Janis Joplin or Jim Morrison died.

Q: Isn't there some kind of Grateful Dead connection?

A: Yes! Deadheads spread the wake-and-bake message of 420 around the country. However, the Grateful Dead did not always stay in Room 420 in hotels on the road.

Q: Isn't 420 Adolf Hitler's birthday?

A: Yes. Hitler was born on April 20, 1889. But 420 hardly commemorates that genocidal murderer. April 20 is also the anniversary date of another horrible buzzkill, the Columbine High School massacre of 1999. Fortunately, that is definitely not 420's origin, as references to 420 date back to the 1970s.

Q: Doesn't 420 refer to the number of chemical compounds in cannabis?

A: Wrong again. There are reportedly 315 chemicals in cannabis.

Q: OK, isn't 420 the number of a bill in the U.S. Congress to legalize weed?

A: Hah! Interesting but wrong. In 2003, California Senate Bill 420 (SB 420), also known as the Medical Marijuana Program Act, established guidelines for Proposition 215, such as how many plants and how much processed cannabis a medical marijuana patient is allowed to have. Oddly, the specific legislator, clerk or aide who apparently numbered the bill in a nod to the 420 tradition has never been identified.

Q: A lot of people say 420 is a police radio code for marijuana.

A: “All units, all units available, please respond to a 420, marijuana smoking in progress.” No. But interestingly, 420 is the radio code for homicide in both fact (the Las Vegas Police Department) and fiction (CSI).

Q: Doesn't 420 refer to the section of the California penal code relating to marijuana?

A: No again. According to noted urban mythbuster Snopes.com, Section 420 of the California penal code refers to obstructing entry on public land.

Q: How about “teatime” in Holland? Don't cannabis smokers light up at exactly 4:20?

A: Sorry. Nor is 420 the date that cannabis was legalized in pot paradise Amsterdam.

Q: Isn't April 20 the best time to plant weed?

A: Hardly. The best time would vary from region to region, and with modern grow houses, you could plant successfully on Feb. 2, even if it's 20 degrees outside.

Q: OK, this one has to be true: Doesn't 420 come from a Bob Dylan song?

A: This is the most charming tale of all. In “Rainy Day Woman #12 and 35,” Dylan repeatedly chants, “Everybody must get stoned!” Even more convincingly, 12 multiplied by 35 equals 420! Sorry, no. Points for creativity, not reality.

If all these stories are false, what's the real deal? The true birth of 420 dates back to the early 1970s, when it became the hour of cannabis consumption among high school students in San Rafael. Even in mellow Marin County, stronghold of the Grateful Dead, no concessions were made to allow puffing during school hours.

So a group of stoners calling themselves “the Waldos” — because they liked to hang out in front of a wall — would pass each other in the halls, exchanging knowing glances and muttering “420 Louis!” One told the San Francisco Chronicle in 2000, “It was just a joke, but it came to mean all kinds of things, like, 'Do you have any?' or 'Do I look stoned?'?” They used 420 as a code word for their activities and the time said activities would take place.

The group met in front of the statue of 19th-century French scientist Louis Pasteur, as well as other spots on school grounds, to get high at 4:20 p.m. It's said that the pack of teens would sometimes roam the campus, searching for a rumored marijuana patch.

The term “420” was widely in use by the end of the 1970s. Deadheads spread it outward like a virus from their San Rafael ground zero. Within a decade, pot smokers were using it across the country and around the world.

The stoner bible High Times started using the term “420” as early as 1990, and later bought the website 420.com, which includes videos, news, horticulture tips, activism and conspiracy links (“Will the LAPD Have Armed Drones Hunting Suspects?”).

Various members of the Waldos have surfaced over the years, showing letters with postmarks from the 1970s that refer to “420” to authenticate their claims. Sources as reputable as Wikipedia and Snopes.com have also confirmed this origin story.

Pop culture is chockablock with references to 420. The clocks and timepieces in Pulp Fiction and later in Lost in Translation are all set to 420. And is it an accident that the score on the football scoreboard in stoner classic Fast Times at Ridgemont High reads 42-0?

An episode of animated comedy Family Guy, naturally titled “420,” is dedicated to the subject. The plot has Stewie and Brian attempting to legalize marijuana. The show includes the classic song-and-dance performance “A Bag of Weed,” which can be seen on YouTube.

Snoop Dogg (now Snoop Lion) said in 2009, “Me and Willie Nelson recorded [a] song in Amsterdam on 4/20, 2009. It was a beautiful day, it was a roomful of smoke. It was historic.” The song, of course, was “Roll Me Up and Smoke Me (When I'm Gone)”.

Awareness of 420 has even spread to Australia. A smoker calling himself “Max Stone” told the Brisbane Times, “You'd go on a job and you'd say to someone in the afternoon that it's going to be 4:20 soon. If they give you a blank look, then you don't take the conversation any further. But if they say, 'yeah,' then you're instantly tuned into the 420 culture that's inside every workplace. It's not as secretive as it used to be.”