The urban environment would play a part in some species. In this case, crows are more likely to be found there than ravens, but that alone isn't enough to rule them out.
In this case, it's Oregon that's important. If you had said a Midwestern or Southern state, we could have eliminated Common Ravens immediately; they aren't regularly found in those areas. Contrarily, if you'd said any of the northern Canadian provinces or territories, we could rule out American Crows; they don't normally get that far north. Both crows and ravens are found in coastal Oregon all year, so we can't use the easiest tie-breaker.