Yank has been used as a degoratory term, I believe it started that way. It refers to when "the colonies" *yanked* away from England.
There are several theories as to the origin of "Yankee". That is not one of them. (In fact, it is demonstrably false.)
--
John W. Kennedy
"The bright critics assembled in this volume will doubtless show, in their sophisticated and ingenious new ways, that, just as /Pooh/ is suffused with humanism, our humanism itself, at this late date, has become full of /Pooh./"
-- Frederick Crews. "Postmodern Pooh", Preface
