Their 2008 book, Generations of Exclusion: Mexican Americans, Assimilation, and Race, decisively concludes a long-running debate about Mexican immigrants.

Telles and Ortiz write:

"Despite sixty years of political and legal battles to improve the education of Mexican Americans, they continue to have the lowest average education levels and the highest high school dropout rates among major ethnic and racial groups in the United States. … However, leading analysts, apparently believing in the universality of assimilation, argue that this is the result of a large first and second generation population still adjusting to American society. … These and other scholars predict that Mexican Americans will have the same levels of education and socioeconomic status as the dominant non-Hispanic white population by the fourth generation."

East Coast pundits, such as Michael Barone and Tamar Jacoby, frequently suggest that, while Mexican Americans may appear to be lagging alarmingly, that's mostly because they've all just recently arrived from Mexico.

After all, whoever saw a Mexican in New York, Washington, or Boston before the last decade or two? So their future is wide open! Pigs could have wings!

This will happen by the third generation, or maybe the fourth—but in any case, Real Soon Now.

Due to "the great, slow, mysterious absorptive alchemy of assimilation" (to quote Jacoby's review in National Review of Barone's 2001 book The New Americans), the descendents of Mexican immigrants will no doubt be flourishing just like the descendents of the Ellis Island immigrants.

So why enforce the borders?

This conventional wisdom, however, doesn't make much sense.

First, three or four generations is a long time to wait for the problems caused by today's illegal immigration to abate.

As John Maynard Keynes pointed out, in the long run, we are all dead. Personally, I will be dead and gone well before the fourth generation offspring of today's immigrants are in their prime.

Second, it's particularly ridiculous to bet the country on a multigeneration-long gamble on illegal immigration when the promised payoff by the 22nd Century is not that we'll then be better off—the pledge is merely that by then we won't be as worse off as we've been for the whole century!

Third, if we don't stop immigration, as we did in 1924, then this “long run” can't even theoretically arrive.

Fourth, and most important, the conventional wisdom is not true.