The question of which color to use for highway center lines (dividing opposing traffic) in the United States enjoyed considerable debate and changing standards over a period of several decades. By November 1954, 47 states had adopted white as their standard color for highway centerlines, with Oregon being the last holdout to use yellow.[1] In 1958, the U.S. Bureau of Public Roads adopted white as the standard color for the new interstate highway system.[42] The 1971 edition of the Manual on Uniform Traffic Control Devices, however, mandated yellow as the standard color of lines separating opposing traffic nationwide. The changeover to the 1971 MUTCD standards took place between 1971 and 1975, with most done by the end of 1973, so for two years drivers still had to use the old and new.