While a wheat bonanza was taking place in eastern North Dakota in the 1880s, a cattle bonanza was occurring in western North Dakota. Ranchers brought their cattle from the southern plains into the Badlands, where there was plenty of grass for their herds of cattle and soon over a half million head of cattle were grazing in the region.

The Little Missouri River Valley, which had been opened by the Northern Pacific Railroad, was an ideal area for raising cattle. There were streams, nutritious grasses which were good for winter grazing, and ravines and coulees which provided shelter. The heart of cattle country was the Badlands, stretching along the Little Missouri River. The future President Theodore Roosevelt was the most famous person who ranched in that area, near Medora. In 1883 he bought his first ranch, the Maltese Cross. During the next five years Roosevelt spent a few months of each year in the area, and kept a small herd of cattle until 1898. Years later, he said, "I never would have been President if it had not been for my experiences in North Dakota."

The bonanza came to a crashing halt in 1886-1887 when winter came six weeks early, with blizzards in mid-November and freezing cold. Cattle died by the tens of thousands, with estimates of seventy-five percent dying. Ranching still continued, but on a much scaled-down version, and ranchers avoided overstocking.