The Potosí trade route reshaped the River Plate's vocabulary as surely as it reshaped its streets.
For two centuries, silver extracted from the Cerro Rico at Potosí — in what is now Bolivia — moved south and east along the Camino Real before reaching Buenos Aires and Montevideo. The trade was in metal, but what it left behind in everyday River Plate Spanish is something more durable: a cluster of slang words for money whose origins run directly back to the colonial mint and the coins it struck.
The clearest case is plata, the ordinary Rioplatense word for money in general. In Castilian Spanish, plata simply means silver. In most of Spain and much of Latin America it still does, or it sits as a somewhat formal register word for cash. In Argentina and Uruguay it has completely displaced dinero in everyday speech — you ask how much something costs, you say you have no plata, you describe someone as wealthy by saying they have a lot of it. The shift is a direct semantic record of a region where silver coin was, for generations, the primary medium of exchange, and where Potosí's output was the economic fact that organised everything else.
Morocho is a trickier trail. The word — meaning dark-complexioned, and by extension strong or vigorous in Rioplatense usage — appears in documents associated with the silver trade referring to a specific grade of alloy, though the chain of evidence here is incomplete enough that caution is warranted. Etymologists continue to debate its Quechua roots; what is not in doubt is that Quechua, the administrative language of the Inca empire that Spain inherited as a colonial convenience, deposited dozens of words into River Plate Spanish precisely through the Potosí corridor.
More directly traceable is patacón, an old word for a large silver coin — the peso of eight reales — that circulated through the Viceroyalty of the Río de la Plata and remains alive today as playful slang for a banknote. The coin was minted at Potosí among other locations, and its name persisted long after the metal itself was replaced by paper. Argentina revived patacón in entirely literal form during the economic crisis of 2001–2002, when Buenos Aires province issued it as an emergency bond; the historical echo was not lost on anyone who used it.
What makes these words interesting is not nostalgia but linguistic mechanics. Slang for money tends to stabilise around whatever form of money was most physical, most handled, most argued over in a given place at a given time. In the Río de la Plata, that thing was Andean silver, arriving by mule across two thousand kilometres of continent. The language simply recorded what passed through its hands.