What river begins in Lewis and Clark County outside of Missoula, Montana?
Missoula, Montana Missoula is a city in the U.S. state of Montana and is the county seat of Missoula County. It is located along the Clark Fork River near its confluences with the Bitterroot and Blackfoot Rivers in western Montana and at the convergence of five mountain ranges, thus is often described as the "hub of five valleys". In 2016 , the United States Census Bureau estimated the city's population at 72,364 and the population of the Missoula Metropolitan Area at 116,130. In the 1990s, Missoula overtook GreatFalls as Montana’s second‑largest city, behind Billings. Missoula is home to the University of Montana, a public research university.
Clark County, Washington Clark County is a county in the southwestern part of the U.S. state of Washington. As of the 2010 census, the population was 425,363, making it Washington's fifth-most populous county. Its county seat and largest city is Vancouver. It was the first county in Washington, named after William Clark of the Lewis and Clark Expedition. It was created by the provisional government of Oregon Territory on August 20, 1845, and at that time covered the entire present-day state.