David McCullough was a young researcher at the US Information Agency when he walked into the Library of Congress in 1961 and chanced upon a photography exhibit depicting the 1889 flood in Johnstown, Pennsylvania, the deadliest in American history.
“I was overwhelmed by the violence revealed in them, the destruction,” McCullough, who was from the same area of western Pennsylvania, later told the Johnstown Tribune-Democrat. More than 2,200 people died, and a thriving coal-and-steel town was submerged in muddy debris because wealthy industrialists had neglected a dam.
