The Odum of Ala Igbo
Hail Biafra!
It is called the United States of America not the US of North America
Likely due to "America" being a colloquial term to refer to North America. Moreover, continental theory is a 19th century phenomenon.
In summary, just because it's old - doesn't mean it's correct. Just like the other ideas of the US founders in the late 18th century like the 3/5 compromise or the disenfranchisement of women