Question: What is the length of the River which has Wild Horse Creek as a tributary ?
Context: The Wild Horse River, formerly known as Wild Horse Creek, is a tributary of the Kootenay River, joining it near the town of Fort Steele, British Columbia, Canada.  The river's canyon was the setting for the Wild Horse Creek Gold Rush and associated "war" during the gold rush of the mid-1860s. 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. The tarpan ("Equus ferus ferus"), also known as Eurasian wild horse or simply, wild horse, was a subspecies of wild horse.  It is now extinct.  The last individual believed to be of this subspecies died in captivity in Russia in 1909, although some sources claim that it was not a genuine wild horse due to its resemblance to domesticated horses. Wild Horse Creek is a tributary of the Powder River in Wyoming.  The USGS has a station on the creek, near Arvada. The Horse Creek Bridge was a covered bridge near the unincorporated community of McKenzie Bridge in Lane County in the U.S. state of Oregon.  Built in 1930, the structure, 105 ft long, carried Horse Creek Road over Horse Creek.  The creek is a tributary of the McKenzie River. Horse Creek Valley is a geographic area along Horse Creek, a tributary of the Savannah River.  It lies within present-day Aiken County, South Carolina (prior to 1872, in Edgefield District / Edgefield County).  The area is alternately referred to as "Midland Valley".  Rising near Vaucluse, South Carolina, Horse Creek enters the Savannah two miles downstream of downtown Augusta, Georgia.  Other communities along Horse Creek include Graniteville, Warrenville, Gloverville, Langley, Burnettown, Bath, and Clearwater.  While Horse Creek itself is rather insignificant, its potential for water power led to early examples of Southern industrialization, including a textile mill at Vaucluse (1830) and William Gregg's Graniteville Mill (1845).  The textile industry continued to play a primary role until the Graniteville Train Derailment and final closure of the Graniteville Mill in 2006. Wild Horse is an unincorporated village in Cheyenne County, Colorado, United States.  The community takes its name from Wild Horse Creek, and began in 1869 as a cavalry outpost, which soon became a railway station and had expanded to a town by the mid-1870s.  After a peak of population and business activities in the early 1900s, the town began dwindling by 1917, when most of it burned down in a great fire.  The town rebuilt, but never at the population or business-service centralization level of its earlier years, and by the 1930s, had begun to dwindle further. Horse Creek is an unincorporated community in western Laramie County, Wyoming, United States.  It lies between Horse Creek to the north, and the South Fork of Horse Creek to the south, along WYO 211 northwest of the city of Cheyenne, the county seat of Laramie County.  Its elevation is 6,506 feet (1,983 m).  Although Horse Creek is unincorporated, it has a post office, with the ZIP code of 82061.  As of the 2010 census, Horse Creek had an estimated population of 39. The Wild Horse Adult Resort and Spa was an adult entertainment complex about 14 mi east of Reno, Nevada, USA that is home to two separate legal, licensed brothels: the Wild Horse Ranch and the Mustang Ranch.  The property is located in a secluded portion of the Patrick Business Park, in the far northern portion of Storey County, at 1000 Wild Horse Canyon Drive, Sparks, NV 89434.  Primary access to the area is via exit 28 off Interstate 80.  The nearby settlement of Patrick, from which the Business Park takes its name (and occupants their mailing addresses), is actually found across the Truckee River and thus is located in Washoe County. The Jocko River (Salish: nisisutetkʷ ntx̣ʷe ) is a roughly 40 mi tributary of the Flathead River in western Montana in the United States.  It rises in the foothills of the Rocky Mountains and flows west into the Flathead at Dixon.  The elevation is 2503 ft where it joins the Flathead.  It is also known as Jacques Fork, Jim’s Fork, Prune River or Wild Horse Creek.  The river breaks into three forks, the North, Middle and South Forks, of which the Middle Fork is considered the main stem.
Answer: 375 mi long