Final answer:
The open range gave way to ranching in the 20th century, resulting in fewer cowboys being needed. The development of barbed wire, expansion of railroads, and emergence of mass production in the cattle industry contributed to this transition.
Step-by-step explanation:
In the 20th century, the open range gave way to ranching, resulting in fewer and fewer cowboys being needed. This transition occurred due to several factors, including the development of barbed wire fencing, the expansion of railroads, and the emergence of mass production and efficiency in the cattle industry.
With the invention of barbed wire, ranchers were able to fence off their lands and limit grazing opportunities along the cattle trails. This restricted the need for cowboys to drive cattle long distances to market.
Additionally, the growth of railroads allowed for the transportation of cattle directly from large ranches to meatpacking plants in cities. This shift in the industry reduced the need for cowboys to transport live animals and instead focused on the mass production of beef.