The first establishment of Buenos Aires by Pedro de Mendoza in 1536 was abandoned due to conflicts between the natives and the Spanish. The city was eventually colonized following its second establishment years later, (in 1580), by Juan de Garay.
The first founder named the settlement: “City of the Saint Spirit and Port Santa Maria of Buenos Aires.” Even though Garay renamed it “City of the Trinity,” the name of the port was maintained and it ultimately prevailed over the latter.
The growth of the city was gradual. In 1750, there were 14, 000 inhabitants. However, the population increased with commercial development, specifically the commercialization of fur. This increase was further induced when, in 1776, the Virrey of the La Plata River designated it as his capital city.
With the proclamation of independence from Spain (1810-1816), the port was opened to free commerce. The prosperity that this brought promoted the further increase of the population, which in 1850 reached 100, 000 inhabitants.
In the 1860s, thanks to the regular exports of fur, wool, meat, and grain the country saw an increase in immigration from Italy and Spain. Additionally there were many Sirio-Lebanese, Polish and Russian immigrants. It is this influx of peoples that imparts on Buenos Aires the cosmopolitan, cultural integration that distinguishes it.
Furthermore, immigration, especially that of the English, brought the city and its port the railroad, the port installations, the tramway and gas lighting. Buenos Aires thus found itself in a privileged position, prevailing over the other Argentine regions. In 1880, the city separated itself from the Buenos Aires Province and created for itself the Federal Capital district, thereby declaring itself the capital of the country.
Throughout the twentieth century and between 1930 and 1950, successive waves of internal migration contributed to defining the city’s eclectic nature, one in which persons from different social strata, cultures, and religions coexist.
Source: 365 Info Buenos Aires