Final answer:
The end of the Cattle Kingdom was caused primarily by environmental and economic changes, most notably, a severe winter known as the Great Die-Up, and the invention of barbed wire which, along with the expansion of the railroad, made large cattle drives unnecessary.
Step-by-step explanation:
The end of the Cattle Kingdom was primarily brought about by a combination of environmental factors and economic changes.
Two significant events in the late 19th century, in particular, contributed to its demise: A severe winter in 1886-1887, known as the Great Die-Up and the invention of barbed wire.
The Great Die-Up resulted in the death of countless cattle leaving ranchers in massive debt and countless losses.
Furthermore, the invention of barbed wire made it easier and cheaper to fence in land, effectively closing the open range and making large scale cattle drives which had been the pillar of the Cattle Kingdom, unnecessary and unprofitable.
In addition to this, the expansion of the railroad also meant that cattle could be transported more easily and efficiently to market, further decreasing the need for long cattle drives. The cumulative effect of these events led to the ultimate end of the Cattle Kingdom.
Learn more about End of the Cattle Kingdom