State of Washington, DC and the State of Washington. What could possibly go wrong? And who would ever mix those two places up?
Already happens.
http://www.bjpenn.com/mmanews/mixup-sfl-confused-u-s-venue-state/
And, there's those that think New Mexico is a foreign country.
http://www.npr.org/templates/story/story.php?storyId=12512979