In 1931, while porcelain and aluminum license plates were still in use, the first issues of steel license plates began to appear. These plates were very sturdy, with a good thickness and a firm color, much more resistant to weather conditions and less fragile than aluminum plates, and, in the case of enameled plates, to impacts and stones. I am not aware that they began to be issued before this date. Ramallo's two 1931 license plates, front and back, were made with a curious system of two thick plates stacked on top of each other: the top one has the stamped letters and numbers, while the bottom one wraps around the edges of the top one like a tin can, giving it a very strong rigidity. For the time, this design must have been quite innovative. (Click on the photo on the right to see the detail.)

For the production of enameled and aluminum license plates, there were probably not as many companies producing them as those dedicated to the manufacture of steel. The enormous variety of these license plates, which can be seen over the four decades of their use, would indicate that there were many more options for municipalities when choosing suppliers to cover their license plate needs year after year. These are some of the companies that produced steel license plates during these years: Olinto Gallo of Rosario, Vanzo of Córdoba, and Barthe of Buenos Aires.I don't know if Compañía Taco and Colmegna continued producing steel license plates, as they were more dedicated to enameled and aluminum plates. As an example, you can see this series of steel license plates from 1935 with at least six different models in terms of size, lettering, and numbers from provinces such as La Pampa, Río Negro, Santa Fe, Buenos Aires, and Entre Ríos.

The year 1936 is an interesting key-date year for steel license plates. It was the last year in which license plates bearing the name of each district were issued in the province of Buenos Aires; starting in 1937, they were issued provincially. (I recently came across an exceptional piece: issued in the Quilmes district in 1938!)

Furthermore, in 1936, a license plate model began to be manufactured that lasted until the early 1960s. It was less elongated and more square with inward-facing edges and fairly standardized in terms of size and font (like the series of five license plates in the left column). Many collectors agree that this is the type of license plate number we are most attracted to. They come in one, two, three, or four digits, although the vast majority have three. If the license plate number was low, with one or two digits, it was customary to precede it with zeros, although there are exceptions to this unwritten rule. The two 1936 license plates from the Avellaneda District, red and yellow, are also examples of this license plate format. These two plates, in particular, also correspond to semiannual license plates. In some districts of the province of Buenos Aires, it is estimated that vehicle license plates were collected semiannually, with a license plate with a different color being issued for each of the two periods. These two license plates mentioned have in common that they are from the same district, year, number, and category; they differ only in their colors. There are more examples:

In the 1930s, the information on steel license plates, as well as on enameled and aluminum plates, was generally minimal: the town, or District in the case of Buenos Aires province, the year, the license plate number, and sometimes the category. Gradually, the name of the province was also added, although it seems that little attention was paid to this information. In Buenos Aires, it was in 1937 that license plates became provincial: until 1936, license plates issued within the province's territory bore the name of each District (although there are exceptions) . No license plates issued prior to 1937 have been found that include the words "Buenos Aires" in any of the Districts in this province. The Tandil District, although it did not clarify the province on its license plates, did make an effort to include on some of its issues a logo of the famous "Moving Stone", which according to history, fell in 1912. The case of the province of La Pampa is curious: in 1937 they had begun to use the word "Pampa" on license plates in some towns in this province. From 1943 onwards, "La Pampa" appeared on most of the plates and on some only "Pampa". Then in 1952, it was wisely decided to put "Prov. de La Pampa" on all license plates, precisely when it stopped being a Territory (also named Governorate) and became a Province. . The small town of Sarah, in La Pampa, had an interesting design for its license plates but without the name of the province printed. Río Negro seems to have opted to clarify the name of the province on its license plates in 1935 by using the full name and later settled simply with "R.N." in some cases. In 1935 Neuqén (still being Territory of Neuquén, with the initials "T de N") would have also done the same . In Santa Fe, provincial license plates began to circulate in 1945 , although there are still license plates from that year with locality names. Most of the license plates in the towns of Santa Fe did not clarify the name of the province in the 1930s, although Humboldt in 1937 was one of the first to do so. In Córdoba, it seems that the name of the province did not appear until the mid-1950s in municipal issues. The oldest from Chubut that I have in the collection, and which have as provincial clarification only the letters "CH", date from 1939 . In San Luis they placed the initials "S.L." in 1930 and 1935 . I do not have many references from the other provinces because I do not have enough pieces.

While interchangeable year-markers were used on license plates in many cases as early as the late 1940s, they became more popular in the 1950s, 1960s, and even the early 1970s. To avoid having to issue a new plate every year, the year-tabs were an important solution. In almost all cases, the tabs were affixed with fine spiral wires and validated with lead seals bearing the initials of each municipality. Surely, the task of removing both license plates from the vehicle, removing the old tab, replacing the new one, sealing it, and replacing the plates must have been cumbersome for the user, and I dare say it must have caused more than one inconvenience to citizens, especially in large municipalities, if this operation were carried out in the municipality itself. The use of scrip in the Districts of the province of Buenos Aires until 1936 was not common, although there are some examples: 1935 for Pergamino, 1935 for Castelli, and 1936 for Mar del Plata for the "Transit" category. The city of Mar del Plata has its own peculiarities regarding license plates. The Partido to which this city belongs is called General Pueyrredón, although all the large-sized license plates issued there say "Mar del Plata" . (Curiously, all the small-sized license plates, for carriages, bicycles, even dogs, say General Pueyrredón ). The scrip used in one of the 1936 license plates do not indicate the year; they refer to some type of category, for the "Transit" license plates (as do the aluminum license plates for Mar del Plata from 1929 and 1931). Another interesting fact is that there is a completely different second design for the "Temporary" category, also issued in this city in 1936. (More comments about the tabs to validate the year on sheet 2.)

After the mid-1960s, the use of the provincial coat of arms and the national flag on license plate frames became quite common. At least the provinces of Córdoba, Chubut, Formosa, Misiones, Salta, and Santa Cruz have examples of this detail. In some cases, decals were applied only for the coat of arms and flag, subsequently sealed with varnish (1967 Matorrales #122). In other cases, printed aluminum discs were glued to the license plate (1967 Pto. Pilcomayo #001). Some decals of the national flag even have the initials R.A. written on them, referring to "Argentine Republic". A third way to add the flag to license plate frames was by embossing it and hand-painting it in light blue and white. Interestingly, in Villa Ascasubi, in the province of Córdoba, license plates for the Truck and Trailer categories used two different styles for the flag.

From having only the minimum necessary information in the early years of issuing plates in our country, with only the name of the town and plate number, or just the year and town, in the case of some porcelain ones, we moved on to having much more complete plates in the late 1960s and early 1970s. Such is the case of the plate for the town of Matorrales, in the province of Córdoba, which in its 1970 plates had information on eight levels: town, plate number, category, a sealed tab with the year and corresponding plate number, province, provincial coat of arms, national flag, and the initials R.A. You couldn't ask for more; it was all there.