David Thompson's Party Camps On The Snake River

George Vancouver explored Puget Sound in 1792.

Vancouver claimed it for Great Britain on 4 June 1792, naming it for one of his officers, Lieutenant Peter Puget. Alexander Mackenzie was the first European to cross North America by land north of Mexico since Cabeza de Vaca of the Narváez expedition. arriving at Bella Coola on the what is now the Central Coast of British Columbia in 1793. From 1804 to 1806 Meriwether Lewis and William Clark scouted the territory for the United States on the Lewis and Clark Expedition. David Thompson, working for the Montreal-based North West Company, explored much of the region beginning in 1807, with his friend and colleague Simon Fraser following the Fraser River to its mouth in 1808, attempting to ascertain whether or not it was the Columbia, as had been theorized about it in its northern reaches through New Caledonia, where it was known by its Dakleh name as the "Tacoutche Tesse". Thompson was the first European to voyage down the entire length of Columbia River. Along the way, his party camped at the junction with the Snake River on July 9, 1811. He erected a pole and a notice claiming the country for Great Britain and stating the intention of the North West Company to build a trading post at the site. Later in 1811, on the same expedition, he finished his survey of the entire Columbia, arriving at a partially constructed Fort Astoria just two months after the departure of John Jacob Astor's ill-fated Tonquin.

Oregon was a distinctly American term for the region. The British used the term Columbia instead. The Oregon Country consisted of the land north of 42°N latitude, south of 54°40'N latitude, and west of the Rocky Mountains to the Pacific Ocean. The area now forms part of the present day Canadian province of British Columbia, all of the US states of Oregon, Washington, and Idaho, and parts of Montana and Wyoming. The British presence in the region was generally administered by the Hudson's Bay Company, whose Columbia Department comprised most of the Oregon Country and extended considerably north into New Caledonia and beyond 54°40′N, with operations reaching to tributaries of the Yukon River.