The Yellowstone River, the largest tributary of the Upper Missouri, rises on the western flank of the Absaroka Range, southeast of Yellowstone National Park in northwest Wyoming. Dropping to the Yellowstone Plateau, the river feeds and then drains Yellowstone Lake; north of the lake, the river cascades through its Upper and Lower Falls and passes through scenic canyons before continuing northward into Montana through Paradise Valley.
Leaving the Rockies at Livingston, the Yellowstone flows ENE across the High Plains of Montana, eventually merging with the Missouri River in western North Dakota, just east of the Montana border. Along the way, major tributaries arrive from Wyoming, draining the east flank of the Absaroka and Wind River Ranges and both sides of the Bighorn Mountains; west to east, these are the Clarks Fork, Bighorn (see The Two-Basin River), Tongue and Powder Rivers (see Powder River Basin).
Just over 700 miles long (including its headwater forks), the Yellowstone is one of the most scenic rivers in the U.S., crossing and draining a spectacular mix of Western landscapes, home to a fabulous diversity of wildlife; among the latter are bison, elk, wolves, grizzlies, mountain lions, lynx, bighorn sheep, mule deer, pronghorn, river otters, prairie dogs, trumpeter swans, sandhill cranes and a host of western raptors and songbirds.
