Red is used exclusively for regulatory road ... of white and black road signs that give specific directions. Yellow road signs are general warnings about something coming up ahead.

A yellow stop sign is a different story, though—that’s actually a throwback to the early days of traffic control, before stop signs universally became red. Regardless of their color ...

As stated above you will find yellow road signs in a number of different places. Regulatory signs indicating restrictions are typically found on major commuter roads, such as Red Routes or outside ...

Now on its 11th edition, the MUTCD sets standards for all road signs, pavement markings and traffic signals, requiring them to all use red, yellow and green light indicators.