The geographic area comprised of Oregon and Washington.
This area tends to be a high level of homogenization and interchangeability area for a few different reasons:
1) They are both very liberal areas politically.
2) One of Washington state's largest cities (
Vancouver, WA) is a suburb of
Portland, Oregon.
3) Their weather is very similar (damp winters with mild summers).
4) Although Washegon falls under the title of "West Coast", Washegon is very different in some ways to California as a whole.
5) Although Washegon falls
under the umbrella title of "Pacific Northwest", it differs enough from Idaho and Montana, that deserves its own label.