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.

The concept of the traffic light actually dates all the way back to the 1860s, where gas-lit signals were placed on the posh streets that lined the Houses of Parliament in London. Of course, back then ...

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 ...