Formation of Wasco County

Wasco County was created by proclamation of the Oregon Territorial Legislature and approval by Congress on Jan. 11, 1854. As created it was the largest county in U.S. history. The county comprised 130,000 square miles and was named for the tribe of Chinook Indians occupying the area near The Dalles. Most of this area was actually controlled by the Shoshone Indians. The county stretched from the Cascades to the Rocky Mountains including parts of what are now Idaho, Montana, and Wyoming. The northern border was Washington Territory and the southern border was California.

The county seat was at The Dalles, it being the only white settlement east of the Cascade Mountains. There were approximately 35 permanent white residents. It also included the military outposts Fort Walla Walla, Fort Boise, Fort Hall, and Fort Bridger. The post office even considered Fort Kearney, Nebraska and Fort Laramie, Wyoming as being in Wasco County.





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