Routes by both land and sea were opening into the Northwest. Intense rivalry grew between the British and American fur-trading interests. Many small trading posts grew along the coast and inland streams. The British, represented by Hudson's Bay Co. and Northwest Co., monopolized trading north of the Columbia and were rapidly increasing their presence on the Columbia. In the East, John Jacob Astor was focusing powerful financial interests in the Pacific Fur Co., which he founded in 1810, hoping to control fur-trading south of the Columbia. He outfitted the ship Tonpuin, commanded by Captain Thorne, which arrived on the Columbia in 1811. He had at the same time dispatched an overland expedition that reached the river the same year. The Tonguin left a colony of men to build a trading post on the south bank, a site they named Astoria for their employer. Another ship, the Beaver, outfitted by Astor, arrived May 10, 1812.

The outbreak of the War of 1812 brought a British man-of-war to the Columbia. In a precipitous move to protect his interests, Astor sold his Pacific Fur Co. to the British Northwest Co., and within a month Captain Black of the British warship took possession of the Astoria post, renaming it Fort George, a name that would persist for years. While the Treaty of Ghent restored the location to the United States in 1818, the trading post remained an asset of the British company until 1821 when it merged with the Hudson's Bay Co. In 1824 Dr. John McLoughlin took command of the post, which he moved to Fort Vancouver some 110 miles upstream near the confluence of the Columbia and Willamette. By 1825, having lost its significance as a trading post, Astoria had become little more than a desolate lookout for company ships. However, upstream the interior regions of Oregon were being settled, by sea and land. Portland was beginning to thrive as a potential center of industry and shipping for the resources of the Willamette Valley and its surrounding country.