The multi-vortex tornado grew to a maximum width of nearly a mile and spent 45-plus minutes on the ground. More than 150 deaths were recorded, making it one of the deadliest tornadoes in history.

On a steamy June night in 1938, a thundercloud parked itself over the badlands near Terry in eastern Montana, unleashing a torrent of rain that sent roiling waters raging down normally dry Custer ...