It turns out that mile marker number 420 keeps getting stolen on highways around Washington State so much that they have changed the marker to say 419.9. The reason people have been stealing the signs is because of the link the number 420 had to marijuana. The term 420 is used to mean the "time" to smoke cannabis or sometimes just used to mean to go smoke.

Next time you are almost to mile marker 420, take a picture of it for me.