Why are traffic lights green, yellow, and red?

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Traffic lights have three colors, and that's all the information that drivers need to get through intersections safely. Green means, "Go." Red means, "Stop." Yellow means, "Stop if it's safe to."

The colors of traffic lights come from signal lights that are used for railroads, which have been around longer than cars. Red was the first choice for "stop," since it's always been associated with things like danger, blood, and fire. It's a very good warning color!

The other colors changed over time. Green is a good choice for "go" since green is the farthest color away from red. If you think about mixing primary colors, green is made from mixing yellows and blues every color but red!

by   (whyzz writer)
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