If there were to be a unification of Canada and the USA, and perhaps Latin America, it would seem that a unifying patriotic theme for North America could be
America the Beautiful, whether you prefer Elvis Presley's or Lee Greenwood's rendition.
Although it wouldn't hurt to change the last line to, "Thy
brighter jubilee!"
Incidentally, the lyrics of that patriotic song includes the line "from sea to shining sea" which is the motto of Canada,
a mari usque a mare.