Bison, any of several species (genus Bison) of ox-like animals of the family Bovidae. Bison may weigh half a ton and stand 6 ft (1.8 m) tall. The American bison, often miscalled the buffalo, once grazed the plains and valleys of Mexico to Canada in herds of millions and was economically vital to Native Americans. Hunted ruthlessly by European Americans, it was almost extinct by 1900. There are still a few herds in U.S. and Canadian national parks and population calculations determine that there are about 15,000 bison in the United States and an equal number in Canada.