We started our Yellowstone trip by driving to the north entrance and hiking to the Boiling River. Along the path we noticed some rather large, fresh-looking footprints and Gary took a picture with his own size 9 (US) foot as a reference. After the hike we drove on to the Mammoth Ranger Station where the ranger without hesitation identified our find as a wolf footprint. It was exciting to know we had been in a wolf's territory since wolves generally stay far away from places people frequent. We have only seen wolves through high-powered spotting scopes.