Leaving the Nipigon River, Moore headed west to Yellowstone National Park. This was not his first visit to the park. In the December 1895 issue of The American Angler, in part 2 of his article “Among the Trouts of the Pacific Slope”, he writes of finding the trout fishing in both Yellowstone Lake and the Gardiner River to be excellent. Of the Gardiner River he wrote, “The stream was perfect for brook work. Wadable through the length we fished, with pleasant pools and sparkling rapids, filled with the genuine old-fashioned wild fish, such as I caught when a boy.”

When he visited in 1895, Moore did not own a camera. This time he did and he put it to good use, photographing many areas of the park, from Yellowstone Lake in the southeast, to Mammoth Hot Springs in the northwest. He also photographed some of the local wildlife, such as elk in a corral, munching on hay, and bears rummaging through a garbage dump. After Yellowstone, Moore headed west 900 miles to Shoshone Falls, Idaho, the next stop on his great Pacific Northwest adventure.