Here’s a fun map from Carl Størmer that compares the GDP of U.S. states to other nations.
(Click for a larger view)
From what I can tell, it seems like it might be somewhat accurate in terms of ballpark figures. For example, Canada’s 2005 GDP was USD1131.8 billion while Texas’ was USD989.4 billion. What's a couple billion?
Anyway it’s interesting to consider.