¡Hola, Wilma! Here are some sites, in case you are doing research on this. From personal experience I can tell you a bit about La Argentina. There are so many Italians there that the pronunciation changed to reflect that. For example, "la silla" (pronounced "lah see-yuh" in castellano has the sound of "la see-juh" in la Argentina.
Of course many Germans migrated to South America during World War II.
P.S. Here is a bit more about dialects, etc. in South America.
oops! Forgot to post it! Thanks, MsSue!
In the case or Argentina, the indigenous natives have been more than 99% displaced by persons of European descent. This is not the case in other countries of South America. I recommend the following reading:
And as for Chile:
2. (part II): http://en.wikipedia.org/wiki/Chile