when was prismatic high-intensity sheeting invented?

[agentsteel53]

I thought it was early (March?) 2006 but I've heard that Missouri was using it earlier than that.

the first time I ever personally saw it was July 2006 in Denver, and the sign shop I work with first got it in August 2006.

[Scott5114]

The image that's questioning Jake's faith:


Naturally it has no EXIF data. This type of signage was installed after Amendment 3 passed, which seems like it was before March 2006.

[J N Winkler]

I don't know when prismatic high-intensity sheeting was invented (one would probably have to look up the patent for that information), but the question is really about widespread commercial availability.  My guess is that MoDOT at least started using it in 2003 or before because I saw it (or at any rate replacement sheeting that looks like it) on Kansas City Interstates when I visited in that year.