The U.S. unincorporated territory of the United States Virgin Islands first required its residents to register their motor vehicles and display license plates in 1917.
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 6 inches (15 cm) in height by 12 inches (30 cm) in width, with standardized mounting holes.
[2] The U.S. Virgin Islands also adopted these standards in 1956, having issued plates 6 inches in height by 12 inches in width (with non-standard mounting holes) since 1952.
[3]