The most important trail, however, was that known as the Great Bannock Trail. The Bannocks of southeastern Idaho made an annual trek to the Bighorn Basin for buffalo. Their trail followed Henrys Fork of Snake River to Henrys Lake, an ancient Bannock rendezvous. From this notable camp the trail went up Howard Creek and crossed the Continental Divide at Targhee Pass. Upon reaching the Upper Madison Valley, the route passed Horse Butte and angled north of West Yellowstone townsite. A camp at Great Springs (now Cory Springs) was situated near the Park boundary.
In Yellowstone National Park, the Bannock Trail winds its devious way across the northern part. There are a half-dozen deviations from the main artery. Wayne Replogle suggests that weather conditions determined these alternations. High ground would be chosen enroute to the plains, but the return trip could be made along the streams. Other considerations might include security, grazing, and game. Entering the Park upon Duck Creek the Trail swung northward across Campanula Creek, paralleled Gneiss Creek to the point of crossing, then quartered southward, crossing Maple Creek and Duck Creek, on toward the head of Cougar Creek and its ample pasture lands.
From this area the Trail goes almost due north to White Peaks, which are skirted on the West. The Gallatin Range was crossed via a saddle north of White Peaks. The Trail then dropped upon the headwaters of Indian Creek and followed down to Gardner River. The route then looped to the left, across Swan Lake flats, on through Snow Pass, down the decline to Mammoth Hot Springs. From Mammoth the Indian thoroughfare struck right, recrossed Gardner River, and followed Lava Creek toward Tower Fall.
The Yellowstone River ford was located just above Tower Fall, near the mouth of Tower Creek. Vestiges of the trail may still be discerned along both banks of Yellowstone River. Other evidences, such as deep grass-sodded furrows, may be seen in the vicinity of junction of the Lamar River and Soda Butte Creek. One branch paralleled Soda Butte Creek to the divide and then descended Clarks Fork to the bison range. The alternate route continued along the Lamar to a secondary divide between Cache and Calfee creeks. This hog's back was then followed to the summit, and the descent was down Timber Creek to its confluence with Clarks Fork. The deep ruts worn by travois in these pilgrimages are still obvious in many places, although unused for three quarters of a century.