The Manhattan Institute released a fantastic study called Measuring Immigrant Assimilation in the United States. As the title suggests, it sets forth a clear statistical methodology for measuring the economic and civic assimilation of different immigrant groups. One interesting passage is:
“The slow rates of economic and civic assimilation of Mexicans apart from other immigrants, and may reflect the fact that the large numbers of Mexican immigrants residing in the United States illegally have few opportunities to advance themselves along these dimensions.”
Could it be that the Federal government's policy toward immigration has the unintended negative consequence of slowing assimilation? If entire groups of people are legally restrained from using the courts and are constantly afraid of being deported, it makes sense that they will stick to their ethnic and cultural communities. Legalization is the only way to turn recalcitrant illegal immigrants into Americans.
On the positive side, assimilation rates for Mexican immigrants since 1995 seems to be increasing, just as other ethnic immigrant groups have done. Despite the government's best intentions and a few laggards, immigration to the United States is a stunning success.