The city of Tacoma and surrounding areas were inhabited for thousands of years by Native Americans, predominantly the Puyallup people, who lived in settlements on the delta. In 1852, a Swede named Nicolas Delin constructed a sawmill powered by water on a creek near the head of Commencement Bay, but the small settlement that grew up around it was abandoned during the Indian War of 1855–56.

In the 19th century the Clark Fork Valley was inhabited by the Flathead tribe of Native Americans. It was explored by Meriwether Lewis of the Lewis and Clark Expedition during the 1806 return trip from the Pacific. The river is named for William Clark. A middle segment of the river in Montana was formerly known as the Missoula River. The river was also referred to as the Deer Lodge River by Granville Stuart. David Thompson used the name Saleesh River for the entire Flathead-Clark Fork-Pend Oreille river system.

Helena: By 1888, about 50 millionaires lived in Helena, more per capita than in any city in the world. They had made their fortunes from gold. About $3.6 billion (in today's dollars) of gold was taken from Last Chance Gulch over a 20-year period. The Last Chance Placer is one of the most famous placer deposits in the western United States. Most of the production occurred before 1868. This large concentration of wealth was the basis of developing fine residences and ambitiou architecture in the city; its Victorian neighborhoods reflect the gold years.