The U.S. state of Kentucky first required its residents to register their motor vehicles and display license plates in 1910. Plates are currently issued by the Kentucky Transportation Cabinet through its Division of Motor Vehicle Licensing. Only rear plates have been required since 1944.
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 tall by wide, with standardized mounting holes.