Something to ponder this weekend from Timothy Noah's book, The Great Divergence:

It would be rash to conclude that immigration's impact on low-wage workers in the United States is a problem in the process of solving itself. It would also be rash to conclude that immigration is poised to do to more skilled workers what it has already done to high school dropouts. For the moment, all we can conclude with certainty is that although immigration has helped create income inequality during the past three decades, it isn't the star of the show. "If you were to list the five or six main things" that caused the Great Divergence, [Harvard professor George] Borjas told me, "what I would say is [that immigration is] a contributor. Is it the most important contributor? No."

(pp 73-74)