> Don't (US) Americans often think of Mexico as part of "South America"?
I've lived in the US for my whole life -- more than four decades -- and this is literally the first time I've seen this abuse of "South American", so I'm going to say, no, its not that common.
> North or Central America would be more correct geographically but the major divider in practice is the US/Mexican border, isn't it?
Well, the US/Mexican border is the "major divider in practice" between US and Mexico, but not between North and South America (when a common term for the Spanish-speaking and Portuguese-speaking countries of North and South America is needed, "Latin America" is the usual collective term.)
Heck, even ignorant Americans abusing a term will just call everyone who seems like they might be Latin American "Mexican" rather than "South American". (Which, wrong as it is in general, is a far better approximation when you are talking about US immigration.)
I've lived in the US for my whole life -- more than four decades -- and this is literally the first time I've seen this abuse of "South American", so I'm going to say, no, its not that common.
> North or Central America would be more correct geographically but the major divider in practice is the US/Mexican border, isn't it?
Well, the US/Mexican border is the "major divider in practice" between US and Mexico, but not between North and South America (when a common term for the Spanish-speaking and Portuguese-speaking countries of North and South America is needed, "Latin America" is the usual collective term.)
Heck, even ignorant Americans abusing a term will just call everyone who seems like they might be Latin American "Mexican" rather than "South American". (Which, wrong as it is in general, is a far better approximation when you are talking about US immigration.)