A stop sign is a traffic sign to notify drivers that they must come to a complete stop and make sure no other cars are coming before proceeding. They are used globally. However, most countries see fewer of them than North America and South Africa, because all-way stops are never used and may even be legally prohibited. In a majority of European and Central Asian countries, as well as Cuba in North America, junctions without traffic lights or roundabouts are controlled by stop signs on minor roads and by white, yellow and black priority diamond signs on the major road. In the UK, the Netherlands, Scandinavia, New Zealand and Australia, stop signs are restricted to situations wherein coming to a dead stop is actually necessary because of severely limited sight lines. At the vast majority of minor intersections in these countries Give Way signs and/or equivalent road markings are used. Finally, at the busier crossing streets, Give Way signs may be replaced by (mini) roundabouts, which also work on the give way (rather than stop) principle.
Stop signs originated in Michigan in 1915. The first ones had black lettering on a white background and were 24 by 24 inches (61 cm × 61 cm), somewhat smaller than the current sign. As stop signs became more widespread, a committee supported by the American Association of State Highway Officials (AASHO) met in 1922 to standardize them, and selected the octagonal shape that has been used in the United States ever since. 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. It was also chosen so that it could be identified easily at night, since the original signs were not reflective. The National Conference on Street and Highway Safety (NCSHS), a group competing with AASHTO, advocated a smaller pink-on-yellow stop sign. These two organizations eventually merged to form the Joint Committee on Uniform Traffic Control Devices, which in 1935 published the first Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) detailing the stop sign’s specifications.
The MUTCD stop sign specifications were altered eight times between 1935 and 1971, mostly dealing with its reflectorization and its mounting height. From 1924 to 1954, stop signs were made with a black stop legend on a yellow field. The reflective sign, initially yellow, was developed by the reflective applications division of 3M spearheaded by Joseph E. Van Kirk, Sr. The sign gained its current white legend/red field color configuration. Red signifies stop on traffic signals, so this specification unified red as a stop signal whether indicated by sign or by light. The original decision to use a yellow background for the stop sign was based “largely on the unavailability of red pigments that would not fade on exposure.” The mounting height reached its current level of 7 ft (2.13 m) in 1971; previously, stop signs were typically mounted 2–3 feet (0.61–0.91 m) above the ground.
The already widespread use of the MUTCD stop sign became law in the United States in 1966. In 1968, this sign was adopted by the Vienna Convention on Road Signs and Signals as part of United Nations Economic Commission for Europe’s effort to standardize road travel across borders. The Convention specifies that ‘stop’ be written in English or the national language and allows an alternative circular yellow sign. Many European countries are party to the Convention. English-speaking countries, the exception being India, are not party to the Convention but usually use the red octagonal stop sign per their own standards, like the MUTCD. Even in countries not associated with either standard mentioned above, the red octagonal stop sign is often used. Unique types of stop signs may still be observed in countries like Japan.
The 1968 Vienna Convention on Road Signs and Signals allows for two types of stop sign, as well as three acceptable variants. Sign B2a is a red octagon with the inscription “STOP” in white. Sign B2b is a red circle with a red inverted triangle with either a white or yellow background, and the inscription “STOP” in either black or dark blue. The Convention allows for the word “STOP” to be in either English or the national language of the particular country. The finalized version by the United Nations Economic and Social Council’s Conference on Road Traffic in 1968 (and in force in 1978) proposed the standard stop sign diameters of 600, 900 or 1200 mm.
The United Kingdom and New Zealand stop signs are 750, 900 or 1200 mm, according to sign location and traffic speeds.
In the United States, stop signs have a size of 750 mm across opposite flats of the red octagon, with a 20 mm white border. The white uppercase letters in small caps forming the stop legend are 250 mm tall. Larger signs of 900 mm (35 in) with 300 mm (12 in) legend and 25 mm (⅞ in) border are used on multilane expressways. Regulatory provisions exist for extra-large 1,200 mm (47 in) signs with 400 mm (16 in) legend and 30 mm (1 1⁄4 in) border for use where sign visibility or reaction distance are limited, and the smallest permissible stop sign size for general usage is 600 mm (24 in) with a 200 mm (7.9 in) legend and 15 mm (⅝ in) border. The metric units specified in the US regulatory manuals are rounded approximations of US customary units, not exact conversions. The field, legend, and border are all retroreflective. In the Vienna Convention on Road Signs and Signals of the UN, the instruction on the sign to stop is specified to be either in English as stop or written in the local language. Some countries use both. The sign’s distinctive design was developed and first used in the U.S., and later adopted by other countries and by the U.N. Despite this, the US is not a signatory to this UN Convention.
Stop signs are often used in North America to control conflicting traffic movements at intersections that are not busy enough to justify the installation of a traffic signal or roundabout. In the United States, the stop sign is not intended for use as a traffic calming device; it is intended to be installed mainly for safety and/or to assign right-of-way for a certain direction. Nevertheless, in the United States, Mexico and Canada, stop signs are commonly deployed as supposed safety measures in residential areas and near places where children play or walk (such as schoolyards), or that experience frequent automobile collisions, making extra precautions necessary. Stop signs may be erected on all intersecting roads, resulting in three- and four-way stops. However, studies have confirmed that stop signs do not offer measurable safety benefits over the Yield approach adopted in the countries listed above based on original European research dating back many decades.
Researchers also found that safety of pedestrians (especially small children) may sometimes be actually decreased. Pedestrians expect vehicles to stop, but many drivers run the “unnecessary” signs. Engine exhaust, brake, tire and aerodynamic noise may all increase as cars brake and then accelerate up to speed. While the initial cost of installing stop signs is low, enforcement costs can be prohibitive, and one 1990 study estimated extra travel costs per intersection as $210,061/year. Finally, where unwarranted multiway stops have been successfully removed with public support, results have included improved compliance at justified stop signs.
A pivoting arm equipped with a stop sign is a piece of equipment required by law on North American school buses. The sign normally stows flat on the left side of the bus, and is deployed by the driver while picking up or dropping off passengers. Some buses have two such stop arms, one near the front facing forwards, and one near the rear facing backwards. The stop sign is retroreflective and equipped either with red blinking lights above and below the stop legend, or with a stop legend that is illuminated by LEDs. Unlike a normal stop sign, this sign requires other vehicles travelling in both directions to remain stopped until the sign is retracted.
In some jurisdictions, most notably Idaho, the traffic code allows for cyclists approaching a stop sign to slow to a “reasonable speed” and yield to conflicting traffic, but does not mandate a full stop unless “required for safety”. This is commonly known as an “Idaho stop” or “stop-as-yield”. The Idaho law has been in effect since 1982 and has not been shown to be detrimental to safety. Cyclist advocacy groups have sought similar laws for other jurisdictions in the United States.
In the UK, stop signs may be placed only at sites with severely restricted visibility, and each must be individually approved by the Secretary of State for Transport. Section 79 of the Highways Act 1980 enables the government to improve visibility at junctions, as by removing or shortening walls or hedges, in preference to placing a stop sign. The former UK practice of using “Halt” or “Slow” at Major Road Ahead signs was discontinued in 1965 at the recommendation of the Worboys Committee. Instead of replacing all the old “Halt” signs with the new Vienna Convention “Stop” sign, “Give Way” became the standard sign at UK priority junctions.
Although all English-speaking and many other countries use the word stop on stop signs, some jurisdictions use an equivalent word in their primary language instead of or in addition to it. Israel uses the image of a hand in a “stop” gesture.
In some Caribbean and South American countries (Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, Dominican Republic, Ecuador, Paraguay, Peru, Puerto Rico, Uruguay, and Venezuela), signs bear the legend pare (“stop” in Portuguese and Spanish). Mexico and Central American countries bear the legend alto (“halt”) instead.
In the Canadian province of Quebec, modern signs read either arrêt or stop; however, it is not uncommon to see older signs containing both words in smaller lettering, with arrêt on top. Both stop and arrêt are considered valid French words and the Office québécois de la langue française (OQLF) notes that the use of “stop” on stop signs is attested in French since 1927. At the time of the debates surrounding the adoption of the Charter of the French Language (“Bill 101”) in 1977, the usage of “stop” on the older dual-word signs was considered to be English and therefore controversial; some signs were occasionally vandalized with red spray paint to turn the word stop into “101”. However, it was later officially determined by the OQLF that “stop” is a valid French word in this context, and the older dual arrêt + stop usage is therefore not considered bilingual but merely redundant and therefore deprecated (à éviter). All newly installed signs thus use either one word or the other, but not both. In practice, the vast majority of signs use “arrêt” in the province of Québec. The “stop” word is usually seen in predominantly English-speaking areas.
The province of New Brunswick has bilingual stop arrêt in English-speaking areas. Acadian regions of Nova Scotia and Prince Edward Island also have bilingual signs. Some areas in Manitoba and Ottawa, Ontario also have bilingual signs, as do entrances to the country through Canada Customs. On First Nations or Inuit territories, stop signs sometimes use the local aboriginal language in addition to or instead of English, French or both. Other parts of Canada use stop. The use of native languages is also commonplace on U.S. native reservations, especially those promoting language revitalization efforts.
Almost all of Europe uses the word STOP in Latin letters; the only exception is Turkey, while Armenia uses a bilingual sign.
The white text on red background appearance is usually the same. Exceptions include Japan, which uses an inverted solid red triangle, and Zimbabwe, which (until 2016) used a disc bearing a black cross.
The Vienna Convention on Road Traffic was concluded at Vienna on November 8, 1968, replacing previous road traffic conventions, notably the 1949 Geneva Convention on Road Traffic, in accordance with Article 48 of the Convention. The United States and China are the most notable examples of non-signatory countries. One of the fundamental principles of the Vienna Convention has been the concept that a driver is always fully in control and responsible for the behavior of a vehicle in traffic. This requirement is challenged by the development of technology for collision avoidance systems and autonomous driving.
On March 1, 1971, the new Highway Code (Straßenverkehrsordnung) for the Federal Republic of Germany came into force, taking into account the World Agreement on Road Traffic Rules and Signs and Signals signed in Vienna on November 8, 1968. In early 1971, Deutsche Bundespost released two sets of stamps to call attention to the new traffic laws. Four stamps were issued on February 18 portraying different road signs (Scott #55-1058) and an additional four stamps picturing traffic signals was released on April 16 (Scott #1059-1062). Both sets were perforated 14. Scott #1057 is a 30-pfennig stamp bearing a Stop sign printed in black, grey and red using the photogravure process. There were 30,000,000 copies of this stamp printed.