What color must a trailer's turn signal lamp be?

A trailer's turn signal lamp must be either red or amber. This regulation ensures visibility and clarity for other drivers on the road regarding the direction the trailer is turning.

Amber signals are often used to indicate a turning or changing lane, as they are highly visible and commonly understood as a warning or indication of intent. Red signals, while commonly associated with brake lights, can also be used in conjunction with turn signals on trailers to provide additional visibility under various driving conditions. The lack of uniformity in color for turn signals allows trailers to maintain compatibility with diverse vehicle designs while enhancing road safety through clear communication of intentions to other drivers.

Therefore, the requirement for either red or amber lamps ensures that trailers meet safety standards designed to prevent accidents and facilitate safe driving behaviors on public roadways.