@Roberta,
I was in bison country last week, and will post some pictures next week. Most were in Wyoming and Yellowstone National Park.
A little trivia on bisons; Americans slayed bisons for their skins, and to rid the Lakota and Cheyenne of their primary source of food and shelter to take over their land. At one time, they numbered less than 1,000, but through private breeding and shelter, they now number over 400,000. Kevin Costner became enamored with the old west, bisons, and Native Americans, when he made "Dancing with Wolves" and have invested to develop Tatanka (the story of the bison), and operates a casino and restaurant in Deadwood, South Dakota - where some in our travel group had lunch.