Roediger has an interesting chapter on that issue in his latest whiteness book - owning a house was an important part of the whitening process for the southern and eastern European immigrants in the early 20th century. It often meant a tremendous financial sacrifice, but they didn't care.
[WS:] Interesting, but Jewish immigration would be a counterexample. Jews were far more likely to form coops than, say, Poles or Italians.
I think what can explain that difference is cultural differences brought from the old world - Poles or Italians were essentially poor peasants or lumpen aspiring to petit bourgeois status, whereas Jews had a long tradition of cooperation and self-management. For example, in pre-WW2 Poland Jews were more likely to be members of some kind of association than Poles. If you look at the social participation data even today, Poland and Italy are rather low comparing to other European countries.
Francis Fukuyama offered an interesting argument in his book _Trust_ where he claims that the key factor is the cultural propensity of a nation to enter economic activity with blood relatives or with unrelated strangers. Of course, that propensity itself is a product of historical factors, such as the importance of the military in the national affairs that facilitates relationships among strangers. Doing business along familiar lines discourages social participation.
This thinking can explain the difference between Irish, Polish or Italian immigrants (mot of whom comes from Southern Italy) - that are the epitome of familialism and Jewish or Scandinavian immigrants who are more likely to enter associations with strangers. I think Germans are a bit of a mix, as some of them came from the peasant stock and formed closed enclaves (like the Amish) while others were of the urban origin and on the forefront of labor organizing (e.g. Pittsburgh steel workers).
Another good example can be British immigration to New Zealand, which occurred at the times when associations were very popular on the British soil - and the immigrants simply brought them with them to NZ and also Australia.
In short, I think it the social relations brought by different immigrant groups from the old world that set the paths in the new world. Heavy presence of groups with predominantly familial type of social bonds (e.g. peasants or petit bourgeoisie of Ireland, Poland or southern Italy) set the familiar-individualistic path and relative absence of cooperation that cut across these familial lines.
Wojtek