Stop Street Road Sign Symbol Caution Traffic Adult Apron
Standard stops signs have a specified size of 75 cm (30 in) across opposite flats of the red octagonal field, with a 20 mm (¾ in) white border. The white uppercase letters forming the "stop" legend are 25 cm (10 in) tall. Larger signs of 90 cm (36 in) with 30 cm (12 in) legend and 25 mm (⅞ in) border are used on multilane expressways. Regulatory provisions exist for extra-large 120 cm (48 in) signs with 40 cm (16 in) legend and 30 mm (1¼ in) border for use where sign visibility or reaction distance are limited, and the smallest permissible stop sign size for general usage is 60 cm (24 in) with a 20 cm (8 in) legend and 15 mm (⅝ in) border. The metric units specified in the US regulatory manuals are rounded approximations of English units, not exact conversions. Field, legend, and border are all retroreflective. Stop signs are retroreflective. In this night photo, the person is barely visible, while the sign is brightly lit by the camera's flash. The stop sign is specified with the English legend "stop" in the United Nations Convention on Road Signs and Signals. This is because 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. Stop signs are often used in North America (including Mexico, where they read "alto") to control conflicting traffic movements at intersections which are not busy enough to justify the installation of traffic signals. In the United States, the stop sign is not intended for use as a traffic calming device; it is meant to be installed mainly for safety and/or to assign right-of-way for a certain direction. Nevertheless, in the United States and Canada, stop signs are commonly used as a safety measure in residential areas and near places where children play or walk (such as schoolyards), or which experience frequent automobile accidents, making extra precautions necessary. It is common for stop signs to be erected on all intersecting roads, resulting in three- and four-way stops. Stop signs are sometimes stolen as pranks. A fatal accident caused by the theft of a stop sign could result in manslaughter charges against the offender. Stop signs are sometimes vandalized. During the presidency of George W. Bush the words war or Bush were reportedly spray-painted on stop signs, hence reading Stop Bush or Stop War. Stop signs originated in Michigan in 1915. The first ones had black letters on a white background and were 24×24 inches, 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 red-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.