We were a little short of Dunraven Pass, in Yellowstone National Park, when we had to wait for several minutes on a frosty morning while a herd of about 50 bison (buffalo) walked slowly past our van. To be surrounded on all sides by the herd was very exciting. We could hear the bison grunting through the open windows. One passed close enough that I could have easily reached out the window and touched it. Despite the roadway and cars, it was a primitive encounter. The enormous creatures, who were for a long time in ascendency in the western lands of North America, made a rather stately march from one side of the mountain to the other.