Above a crude trading post built of driftwood caught in the bend of the river, the Astor interests in 1811 raised the first American flag to float over a permanent settlement in the Pacific Northwest. As a sequel to the War of 1812, Fort Okanogan passed to the North West Company, then to Hudson’s Bay Company.

The original buildings of the Okanogan post were replaced in September 1815, by a new dwelling house with large dining hall, two good houses for the men, and a trading post. This establishment lay across the triangular flat and on the Columbia River. It was surrounded by palisades. Brass four-pounders, located at strategic points, discouraged attack. The Okanogan post declined when the Hudson’s Bay Company broke a new trail for its brigade along the Similkameen and Coquilla Rivers to Fort Hope on the Fraser River.

It was abandoned by them after the Treaty of 1846, which defined the present boundary between Canada, and the United States. In the early sixties, some of the buildings at Fort Okanogan were still standing, but now there are only the depressions in the ground where the cellars were dug. Clearer traces of original buildings remain in a spot a mile or more distant—the second Fort Okanogan. A flood in 1894 swept away the timbers left from the first fort, and a stony beach now covers most of the site. Today, Fort Okanogan State Park features an interpretive center for Old Fort Okanogan. The park is located four miles northeast of Brewster on a bluff overlooking the Columbia River.