While Butte was booming during the 1880s and ’90s, events conspired to end the Old West cattle days on the eastern prairies. The winter of 1886–1887 has been made most famous by the grim drawing of the Last of the 5,000 by artist Charlie Russell. A very dry summer led to a long, extremely cold winter. The warm-weather longhorn, summered on the drought-stricken plains, died in huge numbers as temperatures remained below zero for weeks. One half to three quarters of the cattle in Montana reportedly froze or starved to death. A single winter ended the era of the great cattle drives.

Sheep had played a part in Montana agriculture since the days of De Smet’s St. Mary’s Mission, but now the number of sheep on the plains increased considerably as ranchers realized that the hardy sheep were a good hedge against losses of the more temperate cattle. In 1870 there were just 2,000 head of sheep in the state, one for every 10 settlers; by 1900, with six million head, sheep outnumbered people 24 to one.

While the railroads opened up the growth of the cattle trade in Montana, they also brought in settlements. The open range was increasingly privately owned. The various homesteading acts of the late 1800s and early 1900s opened public land for settlement. With the hegemony of the big cattle outfits broken after 1886, homesteaders set up along the fertile valley bottoms, fencing off some of the best range and water access.