Vehicle registration plates of New Mexico
The U.S. state of New Mexico first required its residents to register their motor vehicles and display license plates in 1912. , plates are issued by the New Mexico Taxation and Revenue Department through its Motor Vehicle Division. Only rear plates have been required since 1961. New Mexico is the only state that specifies "USA" on its license plates, so as to avoid confusion with the country Mexico, which it borders to the southwest. Passenger baseplates. 1912 to 1960. In 1956, the United States, Canada and Mexico came to an agreement with the American Association  of Motor Vehicle Administrators, the Automobile Manufacturers Association and the National Safety Council that standardized the size for license plates for vehicles (except those for motorcycles) at in height by in width, with standardized mounting holes. The 1955 (dated 1956) issue was the first New Mexico license plate that complied with these standards. County coding, 1947–74. New Mexico established a numeric county-code system for its passenger and truck plates in 1947. Santa Fe County was assigned code 1, while the remaining counties were assigned codes 2 through 31 in order of the number of registered vehicles in the county . Following shifts in these numbers, codes 2 through 31 were re-allocated in 1948, after which they remained constant. Los Alamos County was created in 1949, and subsequently assigned code 32. The codes were discontinued on passenger plates in 1972, and on truck plates in 1975. From 1976 until sometime after 1996, the county of issuance was displayed on a sticker at the top of the plate. Cibola County was created in 1981, after the codes had been discontinued.