The replacement of new license plates with the year printed or stamped on the license plate, which probably began around 1913, lasted for decades in many municipalities. Year after year, new plates were made and the previous year's were discarded, although it is estimated that many municipalities required the return of old plates to issue new ones. The number of unused license plates must have been significant in all localities, and in many cases, they accumulated for decades on municipal shelves and warehouses. Added to this was always a significant surplus of license plates in each category, since it was never known the exact number of new vehicles that would be registered in each case throughout the year, and unused remnants remained. Some of this material was salvaged over the years, but most of it was lost as the municipalities dumped them in the landfill or sold them for scrap during general cleanups.

Some of this large volume of license plates for each category to be manufactured in each period was alleviated with the use of annual validation tabs. These became very common in almost all provinces, but only towards the end of the 1950s and beginning of the 1960s. In many cases, however, the system of releasing new plates every year continued until the beginning of the 1970s. As an illustrative fact, I can mention that the most recent printed license plate date I have is from 1971 and is from the town of José de San Martín in the province of Chubut. On the other hand, the lowest-dated license plates with tabs in the collection are from 1933 (such as the license plates of the City of Buenos Aires). In the photo album you can see many examples of license plates from the same year that have tabs and others that have the date stamped on the plate: enter the year you wish to explore in the search engine . The shapes, colors, and material of the tabs indicating the year are extremely varied and could be located anywhere on the plate, depending on the designer.

Within the categories that we can find in the steel plates, there are basically the same ones that existed for the enameled and aluminum ones: Automobile (Auto/Automovil), Truck (Camion), Pickup (Cta/Camioneta), Flatbed (Chatita), Trailer (Acoplado), Bus (Omn/Omnibus), Private (Particular), Rental (Alquiler), Taxi, Test (Ensayo), Temporary (Temporal), Official (Oficial), Doctor (Medico); and in addition, other interesting ones emerge such as: Off-Radio (Fuera de Radio), Rural, Small Truck (CTO/Camioncito), Delivery Truck (Camion de Reparto), Solid Tire (Llanta Maciza), Trailer (Remolque), Salesman (Viajante), Flatbed Car (A CH/Auto Chatita), Remisse, Jeep, Free (Gratis), No Charge (Sin Cargo), Test (Prueba), Duplicate (Duplicado) and Judicial Power (Poder Judicial). There are categories that are not easy to interpret such as: OMC, F, AP and RP that are found in a series of plates from the town of Cafayate, province of Salta , and the "Campaign" (Campaña) category used in plates issued in Tucumán.

In many cases, the categories mentioned are self-explanatory, although others deserve a few lines: the "Outside Radius" (FR/FdeR/Fuera de Radio) category is one of the most curious . The most common explanation I received was that these license plates were for vehicles used outside the urban radius, mostly in the countryside, and therefore paid a slightly lower tariff than regular vehicles.

Another interesting category is "Jeep" which was used specifically for the popular Jeep brand vehicles of the time. The "Rural" category suggests more of a rural street vehicle, like the classic Ford Falcon Rural of the 1960s and 1970s, rather than agricultural vehicles, although I remain unsure until more reliable information is available. The "Test" (Prueba) and "Trial" (Ensayo) categories were commonly used in car or truck dealerships for demonstration or test vehicles. License plates labeled "Duplicate" (Duplicado) were replacements for damaged or lost original license plates."Provisional" (Provisoria) license plates were issued for use pending the arrival of definitive ones. "Solid Tire" (Llanta Maciza) license plates were for heavy vehicles that used solid rubber tires, meaning they did not have pressurized inner tubes. The "Salesman" (Viajante) category is another curiosity and is rarely found. Plates with legends like "Free" (Sin Cargo) or "No Charge" were mostly used by municipal or City Council staff. Those marked "Official" were probably intended for the Mayor, Justice of the Peace, Commissioner, Councilors, Deputies, Senators, and Governors, but are described on a separate sheet.

In many provinces, license plates ceased to be issued by locality (or by District in the case of the province of Buenos Aires) after a certain year, and adopted a single provincial license plate. Not all provinces adjusted to this system and continued using the ones issued by each municipality. In the case of the province of Entre Ríos, it adopted the system of a single provincial license plate early on in 1931 (those issued by locality in previous years) . Although there were municipalities, such as Concepción del Uruguay (license plate #25 of 1954), that continued with their local license plates, everything seems to indicate that Entre Ríos was one of the pioneering provinces to unify its system. The province of Buenos Aires is another example of early change, as 1936 was the last year in which license plates were issued with the names of the different Districts (Partidos): according to my calculations, 109 that year. By 1937, they were already issued as the Province of Buenos Aires, a period that lasted until the end of the 1960s. At this point, it's worth mentioning that for some reason still unknown to me, the General Pueyrredón district issued all its plates under the name Mar del Plata instead of General Pueyrredón, although there must have been a valid reason. I also can't explain how there were plates for Olivos and Bernal , given that they weren't districts at all. I currently have plates for 112 different districts in the province of Buenos Aires, leaving 12 left. Some districts in this province changed their name, but only after 1936, so they have the previous name on their issues: the Caseros plates correspond to what was later called the Daireaux District; 6 de Setiembre issued plates with that name, which was later changed to Morón. In turn, the Las Conchas District eventually became the Tigre District.

La Pampa province began in 1955 with blue and orange provincial license plates as ;n"Eva Perónn Province;n" (described on a separate sheet) and later simply as La Pampa (#09-153 in the left column). Corrientes province appears to have done so in 1957, San Luis province in the mid-1950s, Río Negro and Neuquén provinces in the early 1960s, and Santiago del Estero province probably in the mid-1960s.

The provinces that persisted in issuing license plates at the municipal level until the 1970s were: Córdoba, Chaco, Chubut, Formosa, La Rioja, Misiones, Salta, Santa Cruz, and Santa Fe (there may be others that I don't have any references to at this time). These provinces did not have unified provincial systems until everything was standardized at the national level and black and white license plates were issued, with an initial lette r assigned to each province (see sheet 4). However, it seems that the change to black and white license plates in the different provinces was not immediate. In many localities in several of them, license plates were still issued in the years 1971, 1972, 1973, and later.

The province of Santa Fe deserves a separate comment, given that it underwent some changes that are still not entirely clear to me, although some theories can be speculated. The last plates were issued in 1945, bearing the name of the municipality and the year printed on the plate (1945 Matilde #319). But also in the same year, 1945, a provincial plate was issued (1945 Prov. Santa Fe #354). From then on, it seems that plates continued to be issued by municipality, but not with the full name of the town, but rather with only two initials (there are also three), three numbers, an aluminum tab with the year, and the name of the Province of Santa Fe. These plates were mostly standardized in size, color, and design: (1959 plate #NG 022 in the left column). I have not seen these plates from years other than 1955 and 1959, so I do not know what happened during 1946 and 1955.