I think it was a mix of factors:
- The largest immigrant groups in Argentina were the Italian and the Spaniards, and the two already shared a lot of history (Romans in Spain, Borbone family in Southern Italy, Arabs all over)
- Language was not much of a barrier for Italians when immigrating to Argentina, but it was for those immigrating to the US
- Immigrations in the US included a greater variety of nationalities and all at the same time, so the birth of "closed circles" based on the common language was more likely to happen.
- Immigration in the US lead to immigrants of a specific geographic provenience to found their towns/ciities and stick together. For example, the large group of Dutch in Pennsylvania, or the Swiss Amish in Ohio, etc.
- Immigration in Argentina came to a halt during the 20th century as Argentina stopped developing and attracting people, whereas I feel that there is still a steady draw of immigrants toward the US.
As a consequence, I believe that integration in Argentina was easier, with fewer nationalities, fewer difficulties, and happened over a limited timespan. Since we are now at the 2-3-4th generation they have already blended seamlessly, the Italian and the Spaniards descendants. To put this in pictures, I see Argentina as a big "grey" area with smaller dots representing us, the immigrants of the 2000's; whereas I see the US as a dotted map all over, with some large areas that are black or white (no reference to skin complexion here), with few larger cities who are grey (I'd say NYC, but I don't know the others).
