(WHTM/NEXSTAR) – On many traffic signals found throughout the United States, there is a small light that is placed in between or off to the side of the traffic signal lights. Sometimes you see them ...

Red and green traffic lights have been around since the 1800s, when British traffic officers used to rotate gas lamps that burned red and green to control the movement of mostly horse-drawn vehicles.

Some things are so ubiquitous that it's easy to forget they're designed for a reason. With more than 300,000 traffic lights set up across the United States, it's easy to take how they look for granted ...

Add Yahoo as a preferred source to see more of our stories on Google. On many traffic signals found throughout the United States, there is a small light that is placed in between or off to the side of ...

PENNSYLVANIA (WHTM) — On many traffic signals found throughout the United States and Pennsylvania, there is a small light that is placed in between or off to the side of the traffic signal lights.

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated. (WHTM/NEXSTAR) – On many traffic signals ...