Anthropologist Ronald Leroy Olson, whose subjects were the Quinault, Tlingit and Kwakiutl tribes, defines the coasts of the Pacific Northwest as the place for rectangular plank houses, from the coastal region of British Columbia to the mouth of the Copper River in Alaska, with one exception: the Athabascan Tseutsaut of the head of Portland Canal, who used temporary brush and bark lodges. The Alaskan people are more likely to use spruce wood, which has characteristics similar to cedar, due to the availability of that resource. Cedar was the material of choice for the coastal people of southwestern Canada, and Washington, Oregon, and Northern California.