"Canada acceding to this confederation, and adjoining in the measures of the United States, shall be admitted into, and entitled to all the advantages of this Union; but no other colony shall be admitted into the same, unless such admission be agreed to by nine States."
I guess the offer's still on! If they do everything states do.
The articles of confederation were superseded by the Constitution, with one caveat. On matters on which the Constitution is silent, the Articles of Confederation are still in effect.