420 - American Urban Legends

You live, you learn. At least I did that today.:)
Saw a pretty big crowd outside our school and pass it without wasting even a breath to guess a reason for it; usual assumption did just fine: college people in the North East like to stay in the sun after such long Winters.:) Smoke:yep and plenty and some funny smellin'. Even so, I was concentrating on my paper to present for Econometrics but suddenly I remeber .. Amsterdam. It cannot be possible I said!!?; it's illegal and in plain site?? hmmmm..probably my mind is playing tricks on me (maybe it is a cigar or something)and since I quit smoking cigarettes last September (and I plan to stay that way) and I rushed through. Only when my office mate ask me what was happening outside, I started to think about it. He suggested that it's a Smoking holiday. I was intrigued by two facts: how can it be a smoke day in the US?? In Europe I would understand but here seems rather impossible. Secondly, the previously experienced smell was still intriguing me. Thus, instead of Jeeves I asked our good friend Google and got the answer that I was suspecting:
20 April is the National pot smoking day, apparently. :))
From here you get a series of possible origins (in the order of plausibility):
1. In the early 1970s, a group of teenagers at San Rafael High School in San Rafael, California used to meet every day after school at 4:20 p.m. to smoke marijuana at the water tower.
2. Marijuana grew wild on or near Highway 420 in Ontario in the 1960s. Whether or not this is true, Highway 420 is the location for an annual legalization protest every April 20th.
3.The term could have possibly come from H. P. Lovecraft's Within The Walls of Eryx which contains the line "My route must have been far from straight, for it seemed hours before I was free of the mirage-plant's pervasive influence... When I did get wholly clear I looked at my watch and was astonished to find that the time was only 4:20". This theory for the origin of 4:20 was first postulated on the official website for the rock band Tool.
4. An ounce of marijuana going for $300, sold gram by gram (@ $15), equals $420.
(source: Wikipedia)
On this page there are also some "refuted urban myths" on the same page which can prove to be interesting for those in the mood.
The whole fact puzzled me still since in such a puritan country that you are not allow to sip a beer in a public place without a (famous) brown paper bag, people dare to do this. My amazedness ceased an hour later,when two or three white&blue striped cars stopped in a hurry and dispersed the students.