Argentina first implemented a four-digit postal code system in 1958, aiming to improve mail distribution efficiency.
However, it wasn't until 1998 that the more detailed and comprehensive Código Postal Argentino (CPA) system was launched, significantly enhancing both accuracy and efficiency in mail delivery.
[1] Until 1998[2] Argentina employed a four-digit postal code for each municipality, with the first digit representing a region in the country, except in the case of the city of Buenos Aires (which had different postal codes starting in 1000 and with the other numbers varying according to the zone).
In order to ease the adoption of the new postal code, the former state mail company (Correo Argentino) provides a look-up feature on its website.
Since several provinces share the same initial, a few odd assignments are found (such as X for Córdoba, A for Salta, and N for Misiones).