June 14, 1903, was a typical, hot Sunday in Heppner, a small farm town in northeastern Oregon. People went to church, ate dinner, and relaxed with family and friends. But late that afternoon, calamity struck when a violent thunderstorm brought heavy rain and hail to the mountains and bare hills south of town. When the fierce downpour reached Heppner, people gathered their children and hurried inside. Most everyone closed their doors and windows against the racket.

The thunder and pounding hail masked the sound of something they likely could not have imagined: a roaring, two-story...