What happened

A transmission-line failure on the interconnected grid linking the Yacyretá Dam and Salto Grande hydroelectric station, reportedly triggered by storm damage, cascaded through automatic grid-protection systems on the morning of 16 June 2019, causing a near-total blackout across Argentina (an estimated 44 million people, essentially the entire country except Tierra del Fuego) and the whole of Uruguay (about 4 million people), with partial impacts reported in southern Paraguay and parts of Brazil. Argentine Energy Secretary Gustavo Lopetegui called the event 'extraordinary' and 'something very serious that shouldn't have happened,' explaining that automatic protective systems triggered a total grid disconnection within milliseconds of the initial destabilization, without human intervention. He said a cyberattack was not among the leading explanations under consideration, and authorities launched an investigation expected to produce results within 10 to 15 days. By Sunday night, about 90% of Argentina's power and roughly 98.5% of Uruguay's had been restored. This was documented as an accidental weather-triggered transmission and cascading-protection failure, not an attack.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.