Wikipedia
At the Argentine national census of 2010 the total population was 40,117,096, of whom 149,493 (0.37%) identified as Afro-Argentine.
The Afro-Argentine population resulting from the slave trade during the centuries of Spanish domination of the Viceroyalty of the Río de la Plata had a major role in Argentine history. Throughout the 18th and 19th centuries they comprised up to fifty percent of the population in some provinces, and had a deep impact on national culture. In the 19th century the Afro-Argentine population declined sharply due to several factors, such as the Argentine War of Independence (c. 1810-1818), high infant mortality rates, low numbers of married couples in this ethnic group, the Paraguayan War, cholera epidemics in 1861 and 1864, and a yellow fever epidemic in 1871. By the late 19th century the Afro-Argentine population consisted mainly of women, who mixed with the large numbers of European immigrants.
Over 5% of Argentines state they have at least 1 black ancestor, and a further 20% state they do not know whether or not they have any black ancestors. Genetic studies carried out in 2005 showed that the average level of African genetic contribution in the population of Buenos Aires is 2.2%, but that this component is concentrated in 10% of the population who display notably higher levels of African ancestry. Today there is still a notable Afro-Argentine community in the Buenos Aires districts of San Telmo and La Boca. There are also quite a few African-descended Argentines in Merlo and Ciudad Evita cities, in the Buenos Aires metropolitan area.