Henry Waxman's Little Brother Must Work For The Arizona Republic
Proportion of the Phoenix area's criminal charges that are made against undocumented people: about 10%.
This is according to the Maricopa County sheriff's department's own records, and in the face of a huge effort by Maricopa law enforcement to target criminal immigrants. Sheriff Joe naturally had no comment.
It also turns out that undocumented immigration doesn't drive down wages or the economy (with the possible exception of a small downward pressure on the very poorest citizens, which could be easily offset by taking advantage of the net economic growth associated with immigration).
So I guess we're down to "they make us have to press 1 for English" in terms of empirical claims about negative effects of immigration on non-immigrants (although I'd wager even here that there are enough citizens who prefer to do business in Spanish that your 1-pressing finger would still get a workout).