Here is a very important study of the mobility of immigrants, looking at second generation achievement. Immigration policy is in effect a 50 – 75 year policy, embracing two or more generations for impact on American society. The authors write:
We find that, both in the past and today, children of immigrants, especially those growing up in poorer families, had greater chances of moving up in the income distribution relative to the children of US-born parents. Children of immigrants from nearly every sending country have higher rates of upward mobility than the children of the US-born.
Whereas immigrants in the past predominantly hailed from Europe, immigrants today have more diverse ethnic backgrounds, coming from various Latin American and Asian countries. (US GDP per capita was more than 7 times higher than in Mexico or China when migration flows from these countries took off in 1970, whereas it that was only 2–3 times higher than in European sending countries circa 1900.)
We might have expected this change in the ethnic mix to have an influence on the rates of intergenerational assimilation. Immigrants today come from countries with lower income levels relative to the United States. Overall, our findings stand in contrast to the nostalgic view that it was easier for immigrants in the past to integrate into the US economy and society.
Geographic mobility is higher. We find that an important explanation for why the children of immigrants are more upwardly mobile is that immigrant families are more likely than the US- born to move to areas that offer better prospects for their children.
Higher education mobility. Immigrants enjoyed a faster rate of educational mobility: for a given level of father’s education, the children of immigrants in the bottom half of the distribution tended to achieve more years of schooling than the children of the US-born.
Source: Intergenerational Mobility of Immigrants in the United States over Two Centuries, by Ran Abramitzky, Leah Boustan, Elisa Jácome, and Santiago Pérez