Why Do We Use Red, Green, and Yellow Colors In Traffic Lights?

2. The Red-Green Gaslight (1868)

The first known attempt at a traffic signal system was introduced in London by John Peake Knight in 1868. It was called the “Semaphore” and used red and green gaslights, along with mechanical arms, to signal “stop” and “go.” However, this system had many limitations and was ultimately swapped out for electric lights.

3. Electric Traffic Signals (Early 20th Century)

The transition to electric traffic signals was a huge upgrade for traffic control. Lester Wire, a policeman in Salt Lake City, installed the first electric traffic signal in 1912. It used red and green lights but lacked the yellow warning light. These early electric signals were manually operated by officers who would switch the lights to control traffic. There was still no automation, but we’re getting there.

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