“In the fall of 1897,” recounts Edson Carr Dayton in his memoir, Dakota Days , “an untoward event occurred of far-reaching consequences.” Dayton was no alarmist; his tone was measured; but he was deep into the sheep-raising boom of West River North Dakota, with a flock of 12,000 on grass, and he was up against the scourge of range: an infestation of scab.