|When it comes to traffic, what’s even more important than to move? Obviously, to stop. Until the way is clear. Talking about security (and that's what traffic is all about), it represents no doubt the most essential of all existing road signs.
The first stop sign appeared in 1915 in Detroit, Michigan. There were a variety of colors used for stop signs until the late 1920s, when the background color was standardized on yellow for maximum day and night visibility. This was a number of years before the invention of glass-bead retroreflectorization for sign faces, so a red sign looked very dark at night.
By 1954, signmakers were able to use durable fade-resistant red coatings for sign faces, so the background color of the stop sign was changed to the present red color. This change also served to distinguish the regulatory stop sign from yellow warning signs and made the color consistent with that of red traffic signal indications, which for decades had used red to signal "stop".
The unique eight-sided shape of the sign allows drivers facing the back of the sign to identify that oncoming drivers have a stop sign and prevent confusion with other traffic signs.
The already-widespread use of the octagonal stop sign became law in the United States in 1966. This sign was later adopted by the UN as part of its effort to standardize road travel. Because of this, English stop signs were used beginning in the 1970s in most European countries.
Although all English-speaking and European countries use the English legend "STOP" on stop signs, some countries use a roughly equivalent word in their primary language instead (or in addition). That's the case of several Spanish-speaking Latin American countries, most Arab countries, China, Taiwan, Iran, Cambodia, Laos, Thailand, South Korea, Canada, Ethiopia and some parts of Canada, the one country in the world with most variations of stop signs and the only one that officially employs “regional” languages on them. Its white legend/red field appearance is otherwise the same. The few known exceptions include Israel, which boasts the only non-verbal stop sign in the world in the form of a white hand, and Japan, which uses the Japanese word for Stop in white type on an inverted solid red triangle.