High Quality Content by WIKIPEDIA articles! The U.S. state of Louisiana first required its residents to register their motor vehicles and display license plates in 1915.Optional types do not use leading zeros in their serials. From 1965 until 1993, Louisiana State Police troop area codes were used as part of the serial on the plate, invariably in the center of the serial. From 1993 until 1996, stickers were used to show the troop. This was done to give some idea of where the plates were issued. However, registrants who applied via the mail got plates with the "X" code, which was used for Baton Rouge.