Nobody knows how many American bison inhabited North America before the arrival of the Europeans. Most estimates range between 30 and 70 million animals. They were, however, the economic cornerstone of the native peoples of the plains, who used almost every part of the animal, whether for food, shelter, weapons, utensils or ornamentation.

A large bull may stand 2 m (6 ft.) high at the shoulder and weigh about 1 t (1.1 tn.). It is the heaviest land mammal native to North America. Among the predators, only the grizzly is strong enough to kill an adult bull, although wolves can take juveniles and weak adults.

Bison are equipped with a sense of smell so keen that it is able to detect odours of other animals farther than 2 km (1.2 mi.) away. They also have excellent eyesight and are quite at ease in the water. Bison are herbivores, and they eat mainly grasses. They have been known to live for up to 40 years in captivity. In the wild they are scattered in reserves within their historical range. They are also on game farms and ranches within and even beyond their former range.

Currently, there is debate in the scientific community about whether to include this species in the same genus as its close relatives, which would mean the species name could change to Bos bison.