The six companies were managed by Ferrocarriles Argentinos which was later broken up during the process of railway privatisation beginning in 1991 during Carlos Menem's presidency.

Finally on March 1, 1948, all the foreign railway companies in Argentina were nationalised under the Juan Perón's administration, creating the State-owned company "Empresa de Ferrocarriles del Estado Argentino (EFEA)", then renamed to Ferrocarriles Argentinos, taking over all the railway lines of Argentina, including passenger and freight services.

National Decree N° 520 (1991) created FEMESA, a State-owned company in replacement of Ferrocarriles Argentinos to operate the urban services in Buenos Aires.

The San Martín freight service was given in concession to private company "Buenos Aires al Pacífico" (then América Latina Logística - abbreviated "ALL").

The trains run on tracks that were also used by the freight companies (such as América Latina Logística), a part of being in bad conditions with no maintenance.

As a result, a new consortium formed by the rest of private companies operating the urbain lines (Ferrovías, Metrovías and Trenes de Buenos Aires) named "UGOFE" took over the Retiro-Pilar branch.

In December 2012, the first locomotives and coaches by Chinese company CSR[2] arrived to Argentina for the San Martín urban service.