Some short-distance passenger services are also operated by another state-owned company, Trenes Argentinos Operadora Ferroviaria, in Chaco Province.

The main lines departed from Retiro station in Buenos Aires to the north through the provinces of Buenos Aires, Santa Fe, Córdoba, Santiago del Estero, Tucumán, Chaco, Formosa, Salta, Jujuy, San Luis, Mendoza, San Juan, La Rioja and Catamarca.

Works -directed by American engineer Richard Maury- continued until 1930 when the overthrow of Hipólito Yrigoyen caused their interruption with only a few kilometers built, while Maury was fired by the de facto government.

In 1972 the line started to operate as a touristic service, under the commercial name "Tren a las Nubes" (Train to the Clouds) After the World War II finished, British and French-owned railway companies in Argentina began proceedings with the purpose of selling their railways due to financial problems to operate those services.

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.

de Buenos Aires, Central Norte, Argentino del Norte, Mildland and Provincial de Santa Fe became part of the same network, renamed "Ferrocarril General Manuel Belgrano" to honor Manuel Belgrano, hero of the War of independence and the creator of the flag of Argentina.

On the other side, the Provincial de Buenos Aires railway remained managed in an autonomous way until 1953 when it was also added to Ferrocarril Belgrano.

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.

The branch projected would run from Yacuiba to Santa Cruz de la Sierra but part of the path was being occupied by the Paraguayan Army.

That same year, Juan Rivero Torres was appointed chief of the Bolivian delegation to help organize the Mixed Bolivian-Brazilian Railway Commission; until 1951, he served as delegate engineer of Bolivia in the construction of the Santa Cruz-Corumbá Railway, thereby forming a rail corridor to connect South America's Atlantic ports with its Pacific ones.

On the other hand, Brazil started to work in Bolivia in 1948, having finished the 625-km length Santa Cruz - Corumbá railway line in 1955.

In the case of the CGBA (that joined Buenos Aires Province with Rosario through a branch from Pergamino) the closure was definite and the building would be later occupied by the National Gendarmerie.

After the entire railway network was nationalised during Juan Perón's administration, the Córdoba Central station started to be operated by recently formed Ferrocarriles Argentinos.

The station remained active as an intermediate stop for trains run by Belgrano Railway to La Quiaca in Jujuy Province.

This railway extended along Buenos Aires Province from its terminus of Puente Alsina in Lanús Partido to Carhué, an important tourist centre by then.

After the nationalisation several improvements were carried out in the line, such as the addition of a rail track between Aldo Bonzi and Libertad to increase frequency of the services.

The modernisation included the purchase of brand-new diesel locomotives by American company Whitcomb in 1951 (with the addition of 15 new ones by Werkspoor in 1955) and the construction of a junction in the Tapiales and Aldo Bonzi stations that allowed ex-Midland connecting its line with Ferrocarril Sarmiento railway near Haedo in Greater Buenos Aires.

Trains ran without passengers from Puenta Alsina to Aldo Bonzi, running back to Tapiales junction where they departed to Buenos Aires station.

The rail tracks were also removed while the Municipality of Rosario made a Convention Center ("Patrio de la Madera") on that place.

By the beginning of the 1990s Ferrocarriles Argentinos's financial situation was catastrophic so the national government led by Carlos Menem decided to restructure the company.

[citation needed] Belgrano Sur line that ran trains on ex-Compañía General and Midland railways was granted in concession to Private company Metropolitano (through its TMB division) in 1994.

The Belgrano Norte line was granted in concession to Ferrovías, a company that owned EMEPA, a hugh railway workshop near Chascomús.

The company also made investments, acquiring new diesel locomotives and coaches, upgrading infrastructure (renewing rail tracks and signalling and replacing the old bridges) along the entire line.

In November 1999 the company was given in concession to Ferrocarril Belgrano Cargas S.A., formed by the Unión Ferroviaria and local cooperative "Laguna Paiva".

Through its intervention, the government of Chaco reestablished many passenger services in the Province, connecting its main cities such as Resistencia or Sáenz Peña with the rest of the region.

The other two branches were originally part of British-owned Buenos Aires Midland Railway that began its operations in 1906, extending its network to the city of Carhué in the south-west of the Province.