In 1956, the U.S. states and Canadian provinces came to an agreement with the Automobile Manufacturers Association that fixed the size for license plates for vehicles, except those for motorcycles, at six inches in height by twelve inches in width, with standardized mounting holes. The 1955 (dated 1956) issue was the first Louisiana license plate that complied with these standards.
Green base with embossed white lettering and border and pelican in center.
The last year that the embossed pelican was featured on Louisiana plates.
Reflective white base with embossed blue lettering and border.
White base with embossed blue lettering and border, Louisiana in red at top.
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.
^Benjamin F. Shearer, Barbara S. Shearer. State Names, Seals, Flags, and Symbols: A Historical Guide. Greenwood Press, 2001. ISBN 0-313-31534-5. Quote from p. 200: "The state of Louisiana began issuing license plates in 1915."