Centuries ago, North America’s largest surviving land animal once roamed the Great Plains-as well as into the East and down to Mexico-in numbers up to 50 million. This fascinating study directed by Ken Burns examines how the bison was slaughtered to near extinction in the late 1800s, to the peril of the indigenous people who depended on its existence, and how conservationists afterwards brought its population back from a few hundred to an estimated 350,000 today. (Two Discs, Widescreen) (240 minutes)