ever see a yellow stop sign before?

Because paint was still a new and unreliable item, they hadn't yet invented a red dye that wouldn’t fade over time.

By 1954, though, sign makers began using a fade-resistant porcelain enamel.

So, the Joint Committee on Uniform Traffic Control Devices declared that, henceforth, stop signs would be red with white lettering.

I'm guessing that this didn't result in all the old ones being removed and replaced though, as the truck in the distant back ground is maybe an early 60's?

https://www.jalopyjournal.com/forum/threads/vintage-shots-from-days-gone-by.428585/page-6474