The warning system was working. The bell was ringing, the red lights flashing, the siren announcing the train already sounding across the fields as a Ford F-600 truck approached the crossing. Behind the wheel was Arnaldo Rubén Bianchini, thirty-five years old, hauling 25,000 kilograms of edible fat and canned goods for a meatpacking company. Witnesses later said the load may have blocked his view, that he simply did not see the train. Whatever the reason, the truck rolled onto the tracks at 7:22 a.m. into the path of the oncoming express. The locomotive struck it at speed, and there was no time for anyone to do anything but brace.

The force of the collision tore the locomotive from the rails. It traveled some fifty meters past the crossing, then tumbled end over end, gouging a deep hole in the embankment, smashing through a boundary fence, and coming to rest overturned in a neighboring field roughly a hundred meters to the south. The carriages behind it crumpled and jackknifed. In a single violent minute, fifty-five people died. It remains the second-deadliest railway accident in Argentine history, surpassed only by the Benavídez disaster of 1970, which claimed two hundred and thirty-six lives. It is also the deadliest collision between a train and a road vehicle the country has ever recorded.

The dead were travelers, most of them strangers to Sa Pereira, caught up in the long Saturday journey south. They had boarded in Tucumán and the provinces beyond, bound for Buenos Aires for work, for family, for the ordinary business of a life interrupted without warning. The injured were carried to nearby hospitals; the dead were laid out as the town, suddenly the center of a national catastrophe, did what it could. Some of the bodies were so badly damaged that they could not be identified at all. Those victims were buried together, in a common grave, their names unknown but their loss no less complete. A thousand residents found themselves tending to the consequences of a disaster that had simply been passing through.

Decades on, Sa Pereira has not let the day fade. The town gathers each February to remember the fifty-five, and survivors and witnesses still recount what they saw with a clarity that time has not blunted. The tragedy reshaped how the country thought about its level crossings, those countless unguarded points where a fast train and an everyday errand can meet with no margin for error. The Mitre line still runs, and trains still cross Route 19. But here the crossing carries a weight no signal can measure, marked by a town that decided the people who died on its tracks would be neither nameless nor forgotten.