Final answer:
The bison nearly went extinct primarily because of overhunting by European settlers, who were supported by government policies aimed at developing the Great Plains for agriculture and railroads.
Step-by-step explanation:
The near extinction of the American bison (Bison bison), also known as the buffalo, was primarily due to overhunting by European settlers. The settlers, equipped with superior technology, engaged in market and sport hunting that drastically reduced the bison population. The original text provides a clear explanation: 'By the late 1870s, the bison population dwindled from millions to a few hundred.' This dramatic decrease was caused by commercial hunting, endorsed by the government to clear the Great Plains for commodity-based agriculture, introduce railroads, and distribute the land to Anglo farmers, which was seen as incompatible with the existence of vast bison herds.