As beaver were depleted, David Thompson warned that their destruction would bring poverty, yet the fur trade continued to drive exploration and commerce across the vast waterways of Canada and the United States. The Hudson's Bay Company and the North West Company sent brigades to establish trading posts and map canoe supply routes over thousands of miles of rivers and streams, hunting and trading for beaver pelts and other furs for shipment to Europe. This expansion brought North West explorer and trader David Thompson west of the Rocky Mountains and south of the 49th parallel, where he established Kullyspel House, Saleesh House, and Spokane House. In 1809, as an agent and explorer for the North West Company, he opened Saleesh House, the first permanent trading post in western Montana, and claimed the region for the British Crown by proclamation. Saleesh House became a busy and economically successful business. In 1821, the North West Company and the Hudson's Bay Company merged and continued under the Hudson's Bay Company flag, and Saleesh House was renamed Flathead House. In the mid-1820s, the operation moved about 10 miles upstream, and in 1846 it was relocated again to Post Creek near today's St. Ignatius to be closer to Indian travel routes and winter camping grounds. In 1847, factor Angus McDonald renamed the third Flathead House Fort Connah. The fur trade operation begun by David Thompson at Saleesh House in 1809 continued for another 50 years under the Hudson's Bay Company flag until Fort Connah was permanently closed in 1871 by order of the US Government.