Yellow Stop Signs

I have a memory from very early childhood that’s so faint I can’t be sure if it’s genuine or merely imagined.  I seem to recall seeing a Stop sign on a seldom traveled California backroad that wasn’t red with white letters as would be expected, but yellow with black lettering.  Had I been dreaming?  A quick internet search revealed that from 1924 until 1954 Stop signs were indeed yellow and black.  The reason for this was that, at that time, chemical companies weren’t able to produce a red pigment that wouldn’t fade after prolonged exposure to direct sunlight.  Few people realize this because prior to the mid 1950’s street photography was seldom in color.   

I’m almost regretful that I’ve discovered this small bit of trivia.  Now every time I watch a movie that’s set in the early 50’s, or before, and I see a red Stop sign I mentally note it as an error and for a few seconds it spoils the illusion that the movie is unfolding and taking place as I watch. 

There’s something else I’d like to add.  I did a search for the words “Yellow Stop Sign” on eBay and was amazed by the results.  Even the most battered and weatherbeaten examples will sell for several hundred dollars.  If you happen across a yellow sign in a junk yard snatch that baby up!  One last question;  Why are Stop signs octagonal?  So drivers can identify them from the back.