The Story Behind Some People Saying ‘War-shington’
When you hear someone from the area say Wa"r"shington, it can catch you off guard.
According to the Washington Post, this is called the "intrusive r" and is the strongest characteristic of the Midland Accent. A theory about this is that when the tongue anticipates the "sh" sound, it begins to curl -- making an "r" sound. Even if someone doesn't speak with a Midland Accent most of the time, many Washington natives have a definite "r" sound present.
The Midland Accent must've carried its way over, causing us to refer to our state as such.