General summary of color-coding for American highway signs: - Black & White is an enforced regulation. - Red is a vehicle collision hazard. - Yellow is a sin

General summary of color-coding for American highway signs: - Black & White is an enforced regulation. - Red is a vehicle collision hazard. - Yellow is a single-vehicle hazard. - Green is city and town locations/distances. - Brown is national landmarks, parks, etc. - Blue is all other information. A few geographical signs, like city limits and bridge names, are also sometimes white but the text is much, much smaller. If it's important, you can read it from far away.