I could not get this site to upload images but I posted them elsewhere and I will provide links.
I have relatives in Indiana, and I noticed street signs that have the high school colors and mascots. I took a couple of pictures. The first one is from Brownsburg, Indiana. The school color is purple and the mascot is a bulldog.
This street sign is from Plainfield, Indiana. The school colors are red and white and the mascot is a Quaker. Quakers were some of the first settlers in the area, there is still a strong Quaker presence there, and I am unaware of any complaints about using a Quaker as the mascot (unlike the complaints about the Indian mascot for the University of Illinois).
Covington, Indiana also has their school color and their Spartan mascot on their street signs but I did not take any pictures.
I really like this idea. Street signs are necessary, functional, and eventually, they do weather and need replacing. I do not know how much these street signs cost compared to traditional street signs but they are functional decoration. Not all of the signs in those towns have the school mascots. The newer subdivisions in Brownsburg and the two main roads through town have the special signs. The signs in Plainfield line U.S. 40, Old National Road, and it looks like the city replaced older signs with the special ones.
This is an idea that could be used to brighten the appearance of S. 4th Street and East Lincoln Highway. Again, I have no idea how much signs like that cost but street signs are necessary.
I think the sans serif font on the Brownsburg sign looks easier to read compared to the serif font on the Plainfield sign.