Doing some research into highways and signage, I have found that some states used to have colored signs... ie: not simply black & white. Mississippi, for example, once used blue, red and green (a different color for each direction)
Well, through the "miracle" of e-bay where I "window shop" for lots of signs, I've discovered another style: partially colored US 16 in South Dakota:
(No, that's not the actual photo... it's a photoshop rendition)
Of course, most of these signs disappeared by the late 1950's/early 1960's... part of AASHTO & USDOT's plan to homogenize highway signage.
As near as I can tell, Arkansas and Missouri had no technicolor signage. Texas didn't either, though they had their own variant of the US cut-out shield:Image courtesy AA Roads
I would love to have seen a colored Arkansas sign, but alas, they never existed. Guess I'll have to make my own someday.