How many regions does the United States have?

That depends upon who is counting.

http://www.google.com/search?q=regions+U.S.&hl=en&tbm=isch&tbo=u&source=univ&sa=X&ei=S-lIUfPAHKqxygHpj4DIDw&ved=0CC0QsAQ&biw=711&bih=453