After president Juan Perón nationalised the Argentine railway network in 1948 it became part of the state-owned company Ferrocarril General Roca.

The market of Plaza Constitución in Buenos Aires was served by carts coming from the South of the province that crossed the Riachuelo through the "Puente de Gálvez".

Because of this, Plaza Constitución was the first option to build a terminus station of a great railway that connected the city of Buenos Aires with the south of the province.

In August 1861, Edward Lumb, a British entrepreneur, requested the concession of a railway line that would run from Constitución to the city of Chascomús, 120 km from Buenos Aires.

Juan B. Alberdi stated "The railroad will join the Argentine Republic better than all the congresses... without the 'iron road' that connects their extremes, the country will be always divisible and divided against all the Legislative decrees".

Finally, on May 27, 1862, the Buenos Aires Legislature promulgated the Law that authorized President of Argentina, Bartolomé Mitre, to enter into a contract with Edward Lumb.

Consequently, the line's route was moved to La Paz (current Lomas de Zamora), where the field was more solid to extend the tracks.

As a result, he traveled to London, where bankers Baring and David Robertson agreed to give the company credit to finance the construction of the railroad.

The company requested Samuel Petro & E. Ladd to take over the construction of the whole railroad, including lands, stations, workshops and rolling stock at a cost of GBP 651,000.

Previously, a big celebration had been held, with a ceremony attended by President of Argentina Bartolomé Mitre and Governor of Buenos Aires Province, Mariano Saavedra.

Some of the stations built were Ranchos, Villanueva, Bonnement, Salado, Chas, San Pedro (then Newton), Rosas, Las Flores, Colorado (then Dr. D. Harosteguy), Pardo, Cacharí, Parish, Pinedo and Azul.

Jorge Temperley, who owned many plots of land in the area, expressed his interest in building a train stop for which he donated the field where the station would be built.

The first extended from Altamirano to Azul (connecting cities as Ranchos and Las Flores) and the other branch from Chascomús to Dolores and Ayacucho (inaugurated in 1880).

The parties finally make an agreement that established BAGSR compromise to build two extensions of the line: one from Azul to Bahía Blanca and the second from Ayacucho to Tandil.

Some of them were Azul (established 1832), Esperanza (now General Alvear, 1854), Las Flores and 25 de Mayo (both 1856), Tapalqué (1863), Saladillo (1864), Arenales (then Ayacucho, 1866), Olavarría (1867) and Benito Juárez (1874).

In 1866 the Government of Argentina and the shipping company Aguirre y Murga signed a deal to establish a passenger and freight service between Buenos Aires, Bahía Blanca and Carmen de Patagones.

The BAEPR also built a line from Bartolomé Bavio (a small town near to Magdalena, at the South of Buenos Aires Province) to Álvarez Jonte, opened in 1892.

The fire that destroyed the Estación Central of Buenos Aires in 1897, obligated the BAEPR to move the terminus station to Casa Amarilla in La Boca district.

The railway's repair shops were originally located in Barracas al Sud station and then moved to Sola, where they operated for more than 15 years.

Therefore, the new workshops were built in 1901 at Remedios de Escalada, 11 km from the Plaza Constitución, were the largest in South America, and employed nearly 2,700 men.

This housing complex was named "Colonia Ferroviaria" By the end of the 1940s, the workshops of Escalada had become a sort of factories, where all type of components and spare parts for the locomotives and coaches were manufactured.

On 26 September 1886, the first train arrived to Mar del Plata station, in the homonymous city, which was the main tourist destination during summer seasons.

In 1910 Mar del Plata was the main beach city of Argentina, receiving a huge number of tourists (most of them members of the aristocracy) during the summer.

Due to the intense traffic of passengers, the railway station exceeded its capacity and the Municipality demanded the company to increase the facilities.

During the first decade of the 20th century, the urban development of Mar del Plata moved from the downtown to the South West (nearest to the coast) so the train station was far from the residences and hotels where the tourist were hosted.

[7][page needed] Since 1884 the BAGSR presented drafts to extend the tracks from Dolores to Mar de Ajó (Atlantic coast of Buenos Aires Province) but this project would not be carried out.

In 1885 the Government granted Dávila y Compañía the construction of a tram line that departing from Olavarría station, ended in the San Jacinto quarry (operated by the same company).

[9] This would have provided a rail link between the two countries in addition to the Transandine Railway, connecting Mendoza in Argentina with Los Andes in Chile, which was opened in 1910.

The railway communicated the suburban areas with the Capital city, carrying agricultural products to the ports of Buenos Aires, Necochea and Bahía Blanca.

Marcelo T. de Alvear (elected President of Argentina in 1922) encouraged cooperation with the British companies, which recovered from the great post-war depression and increased their profits 5% per year since 1921 (and 9% since 1924).