<P> In 1927, the American Association of State Highway Officials, or AASHO, published the Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs to set standards for traffic control devices used on rural roads . This was followed by the Manual on Street Traffic Signs, Signals, and Markings, which set similar standards for urban settings . While these manuals set similar standards for each environment, the use of two manuals was decided to be unwieldy, and so the AASHO began work in 1932 with the National Conference on Street and Highway Safety, or NCSHS, to develop a uniform standard for all settings . This standard was the MUTCD . </P> <P> The MUTCD was first released in 1935, and set standards for both road signs and pavement markings . Since that time, eight more editions of the manual have been published with numerous minor updates occurring between, each taking into consideration changes in usage and size of the nation's system of roads as well as improvements in technology . </P> <P> In 1966, Congress passed the Highway Safety Act, P.L. 89 - 564, 72 Stat. 885 (1966), which is now codified at 23 U.S.C. § 401 et seq . It required all states to create a highway safety program by December 31, 1968, and to adhere to uniform standards promulgated by the U.S. Department of Transportation as a condition of receiving federal highway - aid funds . The penalty for noncompliance was a 10% reduction in funding . In turn, taking advantage of broad rulemaking powers granted in 23 U.S.C. § 402, the Department simply adopted the entire MUTCD by reference at 23 C.F.R. 655.603 . Thus, what was formerly a quasi-official project became an official one . States are allowed to supplement the MUTCD but must remain in "substantial conformance" with the national MUTCD and adopt changes within two years after they are adopted by FHWA . </P> <P> The 1971 edition of the MUTCD included several significant standards; it required all center lines on two - way roads to be painted in yellow (instead of white, which was to demarcate lanes moving in the same direction), and required that all highway guide signs (not just those on Interstate Highways) contain white text on a green background . Most of the repainting to the 1971 standard was done between 1971 and 1974, with a deadline of 1978 for the changeover of both the markings and signage . </P>

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