It is difficult to establish the exact date when license plates began to be used on vehicles registered in this province. The oldest one I have in my collection dates from 1920, from the city of General Roca. Their use was regulated by the municipality of each locality. 

The chronological use of porcelain, aluminum, and steel license plates coincides with that of the rest of the provinces; there is not much to comment on in this regard. License plates with the town name and the date printed on the plate were issued up to and including 1960, although starting in 1949, some towns began using interchangeable seals with the year on the same base plate.

In 1959, officials began to talk of using standard provincial plates. This project was officially called the "Single Plate". The Decree 137 of February 19, 1960, regulated the use of these plates, with the following initial text:

Having seen file No. 13,478-A-59, from the Ministry of Government Registry, which contains draft models for license plates for vehicle registrations to be used in the province; draft coding and numbering; colors, measurements, and seals; and the information provided by the Directorate of Municipal Affairs, the Governor of the Province

DECREES:

Article 2: For the motor vehicles indicated in points a), b), and c) of the rate scale approved by Decree No. 75 of January 29, 1960, the license plates shall be thirty-six by fifteen and a half centimeters (36 x 15.5 cm). The same dimensions apply to funeral vehicles, tractors, and vehicles used exclusively for traction, as mentioned in point d) of said scale. License plates for motorcycle cabs, motorcycles, scooters, motorized vans, tricycles, and motorized bicycles shall be sixteen and a half by ten and a half centimeters (16.5 x 10.5 cm).

Article 3: License plates shall have a black background and white numbers and letters, with the exception of taxi license plates, which shall have a red background and white numbers and letters. Official and free of charge, with a white background and black numbers and letters.

Article 4: The seal shall be renewed annually and shall contain the year, type, and category of the vehicle.

Article 5: Two letters shall be assigned to each municipal entity as a coding system, which shall not be repeated under any circumstances. The numbering shall begin with 001 for each and generally for all vehicles listed in points a), b), and c) of the fee scale, as well as funeral vehicles, tractors, and vehicles used for traction. The same system shall be used for motorcycle cabs, motorcycles, scooters, motorized vans, tricycles, and motorized bicycles.

Article 6: A public tender for the provision of license plates shall be issued through the Supply Department.

Considering the date the decree was published in the Official Gazette of the Province of Río Negro, March 19, 1960, it is likely that until these new license plates were put out to tender, approved, issued, sent, and distributed throughout the province, their use on vehicles was delayed for a significant amount of time. Surely the ones used in 1959, which were still local, or even those issued in 1960, or had a 1960 sticker, would remain valid throughout that year.

The coding list for the localities of Río Negro implemented in the Single License Plate is worth mentioning: as a general rule, the first and last letters of the name of each municipality were used. For example, General Godoy was coded GY (General GodoY), San Carlos de Bariloche was coded SE, and General Roca was coded GA. But there are a number of localities where these two letters coincide, so additional rules were chosen to distinguish one from the other:

1.- If the name consisted of a single word, the second and last letters were used.

2.- If the name had more than one word, the first letter of the first word and the first letter of the last word would be used.

These rules can be seen in the following example.

VIEDMA   VA

VALCHETA   AA

VILLA REGINA   RA 

SAN CARLOS DE BARILOCHE  SE

SAN ANTONIO OESTE   SO

3.- In the case of a coincidence of initial letters, and after having exhausted the first two rules, different options were used, and it could be safely stated that other supposed rules contradicted each other when one tries to narrow it down and find a definitive general rule. It will be necessary to find bibliography that devotes more detail to this topic.

CERVANTES   CS

CHICHINALES   CH

CINCO SALTOS   SS

The letters assigned to the Unique Plates of each locality were:

There are at least three towns that apparently were not assigned license plates: Chelforó, Clemente Onelli, and El Cuy. Vehicles were probably never registered there. Darwin and Río Chico do not appear on the original list of assigned letters issued in the original decree, although they did have their own license plates. They may have been added to the list years later.

License plates with pictures were rarely used in this province: to date, no other pieces have been found other than those issued in Bariloche promoting skiing, fishing, and mountaineering. There were three versions of these types of license plates, all three can be seen here. Plate 039 has a pine tree on its tab and was used in 1957; plate 1180 shows a skier on the tab and was used in 1958, and plate 338 has a trout on the tab and dates from 1959. At the bottom, all three plates have a slogan: SNOW-FORESTand LAKES on the first two and SKI-FISHING-CLIMBING on the third one.

In San Antonio Oeste, on the other hand, what was used was a plate with a picture, promoting the Las Grutas Beach, and this half license plate was surely placed on top of the provincial license plate in use in those years.

The Lobería, located near the provincial capital of Viedma, was also promoted with a small, graphic license plate reading "Visit La Lobería". This license plate was used as early as the early 1970s with the new "R" license plate.

One of the most beautiful license plates issued in Río Negro is the one used for several years in the 1950s in General Roca. Curiously, the abbreviation for the "Camioneta" category was placed at an angle, as seen in the photo. Below the "59" tab, the year "53" appears embossed, and it was surely the latter year that these unusual license plates first came into circulation.

As in the rest of the provinces, official plates were also issued in each locality. Such is the case with Plate No. 6 for Ñorquinco. The official and "free" provincial plates of the 1960s were also issued in black and white, as stipulated in Article 3 of the decree..

(*) My most sincere thanks and recognition to my friend and colleague Helga, who has dedicated much time and effort in collecting data on the history of the plates of Bariloche, Río Negro and National Parks, and has kindly given me everything detailed in the paragraphs of Unique Plate