Hi Livvie, Well I don't have an answer to your Q, but going to your link I noticed an interesting link posted there by Harry; "In 1923, Illinois officially declared that English would no longer be the official language of Illinois - but American would be."
The link goes on to say that Illinois has since changed its official language to English, but still has statutes on its books referring to the American language!
I think the transition has already been made. According to Professor Henry Higgins (of My Fair Lady fame) "In America they haven't spoken English for years."