Reddit reviews Replenished Ethnicity: Mexican Americans, Immigration, and Identity

Languages typically die off by the 3rd or 4th generation. A book I read a few years back, Replenished Ethnicity goes into how a steady influx of immigrants can prolong the attachment to one's ancestral home.

Right now, the largest immigrant communities in the US are Asian and Latin American... as such, these communities are likely to have stronger cultural ties to their nation of origin - including language.

With Western Europe, we simply don't have the same degree of immigration as we used to - there is no 'new blood' to keep cultural ties current.

Although most of us are too far removed from our ancestral origins for the language to persist, many cultural practices have taken firm hold - a lot of regional variation in the US is directly tied to the origins of their immigrants.

Growing up in Wisconsin, while I don't consider myself "German" I do feel a lot more comfortable/familiar visiting Germanic and Nordic regions of Europe than I do when visiting anywhere else. The humor, food, and overall way that people carry themselves is almost identical to what I grew up with.

edit: There are still many of us whose grandparents or great-grandparents who emigrated from Europe; I do know a few people that still speak Polish/German/Norwegian in their homes, but it's a minority.