American bison
Habitat and trails

American bison live in river valleys, and on prairies and plains. Typical habitat is open or semiopen grasslands, as well as sagebrush, semiarid lands, and scrublands. Some lightly wooded areas are also known historically to have supported bison. Bison also graze in hilly or mountainous areas where the slopes are not steep. Though not particularly known as high-altitude animals, bison in the Yellowstone Park bison herd are frequently found at elevations above 2,400 m (8,000 ft), and the Henry Mountains bison herd is found on the plains around the Henry Mountains, Utah, as well as in mountain valleys of the Henry Mountains to an altitude of 3,000 m (10,000 ft). Reintroduced plains bison in Banff National Park have been observed to roam mountainous areas, including high ridges and steep drainages, and archaeological finds indicate that some bison historically may have spent their lives within mountains while others may have migrated in and out of mountains.

Those in Yukon, Canada, typically summer in alpine plateaus above treeline. The first thoroughfares of North America, except for the time-obliterated paths of mastodon or muskox and the routes of the mound builders, were the traces made by bison and deer in seasonal migration and between feeding grounds and salt licks. Many of these routes, hammered by countless hoofs instinctively following watersheds and the crests of ridges in avoidance of lower places' summer muck and winter snowdrifts, were followed by the aboriginal North Americans as courses to hunting grounds and as warriors' paths. They were invaluable to explorers and were adopted by pioneers.

Bison traces were characteristically north and south, but several key east–west trails were used later as railways. Some of these include the Cumberland Gap through the Blue Ridge Mountains to upper Kentucky. A heavily used trace crossed the Ohio River at the Falls of the Ohio and ran west, crossing the Wabash River near Vincennes, Indiana. In Senator Thomas Hart Benton 's phrase saluting these sagacious path-makers, the bison paved the way for the railroads to the Pacific.
keywords:existence