Incidentally:

My sister and brother-in-law are professors of political science at the University of Illinois, and are in New Orleans this week attending a professional/academic meeting.

They passed along the following information, from a paper presented at the meeting yesterday or the day before:

A study of US communities formerly tolerant of undocumented workers shows that the crime rate always begins rising to a significant extent immediately upon institution of an immigration "crackdown."

The reason is that decent hardworking people who formerly cooperated with police to solve crimes in their economically-disadvantged neighborhhoods suddenly find themselves in a position where the cops are their enemies. Less communication, fewer arrests and prosecutions, more criminals remaining on the streets with increasingly emboldened attitudes.

The basically virtuous character of the overwhelming majority of illegal aliens should not be ignored. As has already been noted above, these folks almost invariably exhibit a much stronger work ethic than homegrown American hirelings, are more productive, require less supervision, etc.

Also, even among those who might not be as virtuous as others, they know they're "illegal" and subject to prosecution, deportation, etc., and therefore are not wont to draw attention to themselves by antisocial behavior. Almost invaraibly, the only thing "illegal" about such individuals is their immigration status.

For non-citizens, the vast majority of our undocumented guest workers are pretty damn good citizens.