Devils horse coach beetle
I lived in Oregon all my life and have never seen an insect like this. It looks and acts like Ocypus olens as Wikipedia describes it. Are these known to be in Oregon? Wikipedia pegs them as a European species.
Ocypus olens is the largest of the rove beetles common in Oregon. (They and many other insects common locally, originated in Europe but have since been transported elsewhere in one way or another.) People seldom see rove beetles because these insects are active at night. Their scorpion-like defensive pose with their tail curved upward typically causes people to think they are true scorpions. They are useful as predators in gardens, landscapes, and farms where they assist in controlling certain insect pests. See http://eol.org/pages/2870631/overview and http://bugguide.net/node/view/141761/bgimage.