David Thompson posts a claim notice at the Columbia-Snake confluence

Background. In early 1810, David Thompson received orders to establish a route to the mouth of the Columbia River. He was associated with the North West Company, which was based in Montreal. His journey in 1811 involved traveling through unvisited territories, including the area between Kettle Falls and the confluence of the Columbia and Snake Rivers, where he interacted with indigenous villages.

Journey to the Confluence. Thompson traveled from Kettle Falls to the junction of the Columbia and Snake Rivers in July 1811. This region had not been visited by Europeans before. He spent time visiting villages along the route to establish good relations, using tobacco as a tool for diplomacy. The legacy claim of a formal notice for the United Kingdom is not supported by the sources.

Arrival at Fort Astoria. Thompson reached the mouth of the Columbia River on 14 July 1811. He found Fort Astoria partially constructed by the Pacific Fur Company. The fort had been built by employees using bark-covered logs. Thompson arrived two months after the Pacific Fur Company's ship, the Tonquin, had arrived.