Why Japan Has Blue Traffic Lights Instead of Green

The reason Japan has blue traffic lights is largely historical and linguistic. In Japanese, the word for 'blue' (ao) was historically used to describe both blue and green colors. When traffic lights were first introduced to Japan, the term 'ao' was used for the 'go' signal, and it was not considered necessary to change it to 'green' (midori) as the nuance was understood. Although the Japanese language has since developed a more distinct word for 'green', the term 'ao' for traffic lights has persisted.