Located on the banks of the Rio de la Plata, the population of the metropolis is 13 million. The city is the national capital, a port city, financial center, and commercial hub for the agricultural riches of the great pampas. As a center of finance, government, manufacturing, population, and commerce, it is similar in importance to Washington, D.C., New York City, and Chicago combined. Its importance in the Southern Cone region of South America is difficult to overstate.
Buenos Aires was founded twice, the second time in 1580, and in 1776 it became the independent capital of the Viceroyalty of La Plata. The first port of the city was the Riachuelo river. Buenos Aires spread north from the Riachuelo towards the delta of the Rio de la Plata. As industry expanded throughout the 1800- 1900s, the city reoriented itself around the river, with nearly 5 million people living in the basin now. As port operations outgrew the canal and moved, its primary official function was as an open sewer for industrial and municipal waste. Poor, opportunistic settlements organized themselves along the unregulated banks. This 200-year environmental-industrial legacy have left the river basin with serious issues of toxicity, vacancy, sedimentation, and regulation. The river is now considered by the Blacksmith Instituteto be one of the most polluted in the world, and these issues are most exaggerated along the urban canalized portion. Industries, ecologies, and communities continue to function along its edges.