A familiar icon of the American West, the Plains bison (Bison bison bison), also commonly called buffalo, is one of two subspecies of the American bison, with the other being the wood bison (Bison bison athabascae). These large mammals once numbered in the tens of millions and roamed North America in nomadic herds. Many Indigenous cultures, especially in the Great Plains, where the species was most abundant, developed strong ties with bison.

By the early 1800s, bison were eliminated west of the Rocky Mountains and east of the Mississippi River. During the 19th century, when European American settlement was expanding into the Great Plains, bison were systematically slaughtered to the brink of extinction. By 1889, only a few hundred wild plains bison remained in the Texas Panhandle, Colorado, Wyoming, Montana and the western Dakotas, as well as a small number in captive herds. Several ranchers gathered up remaining bison, preserving the species, but also experimenting with hybridizing bison with cattle. Beginning in the early 20th century, conservation herds were established to rebuild populations.

Currently, there are approximately 20,500 Plains bison in conservation herds and an additional 420,000 in commercial herds. While bison are no longer threatened with extinction, the species faces other challenges. The loss of genetic diversity, combined with the loss of natural selection forces, threatens the ecological restoration of bison as wildlife. A low level of cattle gene introgression is prevalent in most, if not all, bison herds.

Together with our partners, we work to conserve the existing bison herds in the United States and continue to cooperatively implement the Department of Interior’s Bison Conservation Initiative. In addition to federal cooperative efforts to conserve existing herds and establish new herds, several state and tribal governments, as well as private entities, participate in restoration of the Plains bison. State-managed conservation herds exist within the species’ historical range in Arizona, Kansas, Minnesota, Missouri, Nebraska, South Dakota, Texas, Utah, Wisconsin and Wyoming. Additional state herds that are external to this historical range exist in Alaska. Native American tribes in several states have restored bison to their lands as well. The Nature Conservancy also manages several herds for conservation purposes. Turner Enterprises manages several herds with dual purposes of conservation and commercial production. The American Prairie Foundation and the World Wildlife Fund have also developed conservation herds. In 2016, the American bison was named the national mammal of the United States.