The BAWR was one of the Big Four broad gauge, 5 ft 6 in (1,676 mm) British companies that built and operated railway networks in Argentina.

Although the construction of this line was proposed by a group of private individuals known as the "Sociedad del Camino-Ferrocarril al Oeste" (in English: "Western Railway Society"), it was financed by the province of Buenos Aires, which was at that time an independent state of the Argentine Confederation.

This grant was fulfilled by a bill presented on 9 January by a financing committee consisting of Dalmacio Vélez Sársfield, Bartolomé Mitre and Mariano Billinghurst.

However, in 1854, when work was about to begin, the Society asked to be exempted from using steam engines arguing that it would be more convenient "to use horses, so cheap in this country, instead of coal, which is so expensive" (this method of powering trains had already been used in Europe).

A law sanctioned by Buenos Aires province's Chamber of Representatives established the donation of public land, free import of supplies and tax exemptions.

A now-discounted popular legend[5] says the locomotive came via Crimea; for example, Raúl Scalabrini Ortiz wrote in Historia de los Ferrocarriles Argentinos (History of the Argentinian railways) (1940), that "it was built for India and used in the siege of Sevastopol, during the Crimean War.

"[6] However, some historians deny this, and research in the 1950s showed that this story is untenable;[7] for example, Julio A. Luqui Lagleyze does not believe this could be the case, "since it uses a different gauge, and the dates of its construction and entrance into the country leave a gap which would not have allowed this".

[11] Contrarily, contemporary reports claim that engines from the GCCR went to Argentina; see for instance Richard Francis Burton who mentions in his "Letters From the Battlefields of Paraguay" (1870)[12] that the train he travelled in was pulled by an "asthmatic little engine—which, after serving its time upon the Balaklava line, and being condemned as useless at Buenos Aires, had been shipped off to Paraguay" [13] A carriage pulled by 30 oxen brought the locomotive from the port to the station.

The outward journey presented no difficulties, but on the way back the overenthuiastic passengers persuaded British mechanic, John Allan, to ask for more speed, which led to a derailment adjacent to Almagro station breaking several metres of the track.

The rails brought from Europe did not reach Flores, so they had to be constructed from wood coated with sheet metal, which jumped every time the train passed over them and the laborers had to run to nail them down again.

On 30 August the opening was almost suspended, because some drunkards tried to tip La Porteña over, an occurrence prevented by Elordi's opportune intervention.While most of the population did not find out, those interested in the business did everything possible to stop the accident from becoming known, and it became clear that it was necessary to make some more adjustments before the inauguration.

On the inaugural journey he was accompanied by, among others, Bartolomé Mitre, Domingo F. Sarmiento, Dalmacio Vélez Sárfield, Estanislao del Campo, members of the Railroad Society and special guests such as local political boss José María Yanquetruz, in military dress.

La Porteña and its carriages, driven by Alfonso Corazzi (also acting as stoker), was waved off from the decorated station by a crowd, and reached San José de Flores village, where a band played the Marcha a Lavalle.

Finally it reached the terminal station, La Floresta, where it was welcomed by a crowd and the company gave a refreshment service to the passengers in the local Café Restaurant.

The route left Del Parque station towards the west, zigzagging through the square, which provoked serious complaints from neighbours who said that their environment was being invaded, to reach what is now the corner of Talcahuano and Lavalle.

From Corrientes it continued straight on to Pueyrredón avenue (previously "Centroamérica"), where it turned sharply and continued onto Cangallo (now Juan Domingo Perón), then returned to a westerly heading to enter the West Market (now Plaza Miserere) and the wooden Once de Septiembre (later replaced by the current station), reached by Ecuador to the west and named after 11 September 1852, the date of the rebellion of Buenos Aires Province against the Federal Government.

The line then followed a route parallel to present-day Bartolomé Mitre up to the triangle formed by the current streets Medrano, Pelufo and Lezica, where the (also wooden) unmanned station Almagro was located.

Continuing to the west, at 10 km from its starting point, between Joaquín V. González (then "Esperanza") and Bahía Blanca (first an unnamed street and then "De La Capilla") it reached Floresta station (wooden).

During the 27 years in which it belonged to the Government of the Province of Buenos Aires, the Western Railway was the line which was most luxurious, least wasteful in its bureaucratic-administrative expenditure and offered the most economical fares and cargo rates.

A Law promulgated in November 1868 obliged the Ferrocarril Oeste de Buenos Aires (FCO) to extend its lines to the Andes with the aim of connecting Atlantic and Pacific oceans routes.

While the route to the Andes was being studied, the FCO extended its tracks to other cities such as Chivilcoy, Bragado, 9 de Julio, Pehuajó and Trenque Lauquen.

In 1873 the convenience of raising the tracks between Plaza del Parque terminus and Once de Septiembre station was already under consideration, due to the rapid urbanisation which had taken place along the route making the train's passage dangerous.

A municipal decree in April 1878 decided to move the terminus to Once de Septiembre but the company delayed its response to the request, despite a concurrent claim from the neighbourhood, until 1 January 1883.

They had good reason for this, which was not related to earnings from its operation, but rather to what was said by the British government minister in Buenos Aires, Edward Thorton, in a report to the Foreign Office.

In his presidential speech of 1887 he announced: "I am planning to sell all public, reproductive works in order to pay our debts, because I am convinced that the State is the worst administrator".

In 1887 the Western Railway has already been condemned to death (...) The unnecessary growth in spending, largely due to the disproportionate increase in employees, the unavoidable increase in capital invested in construction, the resulting decrease in returns and the rise in ticket prices made up a definite intent to sabotage: the Western Railway would quickly be discredited in the public opinion.

The governor argued that millions of gold pesos would "come from abroad to increase public wealth", to be "invested in drainage and irrigation, general and municipal roads and health and surfacing projects".

Historian William Rögind found the sale of the railway to be imposed by the "wasteful provincial administration", at that time headed by governor Julio Costa.

While belonging to the British, the railway's reach was increased in the centre of Buenos Aires Province and La Pampa, and was extended south of Mendoza.

By 1945 the British and French companies were seriously affected by the World War II, beginning contacts with the Government of Argentina to sell their railway lines that still operated in the country.