What is the length of the River which has Wild Horse Creek as a tributary ?
Powder River (Wyoming and Montana) Powder River is a tributary of the Yellowstone River, approximately 375 mi long in northeastern Wyoming and southeastern Montana in the United States. It drains an area historically known as the Powder River Country on the high plains east of the Bighorn Mountains.
West Fork River The West Fork River is a principal tributary of the Monongahela River, 103 miles (166 km) long, in north-central West Virginia in the United States. Via the Monongahela and Ohio Rivers, it is part of the watershed of the Mississippi River, draining an area of 881 square miles (2,284 km²) on the unglaciated portion of the Allegheny Plateau.