Help wanted regarding immigration statistics

I had a most fascinating (and surprisingly polite) discussion with a liberal the other day regarding illegal immigrants. My friend kept arguing that we owe the illegal immigrants in our country citizenship, welfare, health care, education, etc., because they’re here and we can’t humanely deny them access to those benefits. I argued that, if we denied illegal aliens protected workplaces, citizenship, welfare, health care, education, etc., they wouldn’t keep coming illegally to America. The same services his emotions tell him to provide for them are the incentives that bring them here in the first place.

My friend absolutely rejected my cause/effect argument. He said a minute number might be rational actors seeking all the benefits America provides, but the others come for “hope.” I responded that this “hope” is all tied up in the services we offer. And so this endless loop of a conversation kept rolling along, with him saying they’re coming anyway, so we should just ignore our sovereignty and owe them services, and I saying that they’re coming only because we give them services, and we have the right to control immigration.

I finally brought the conversation to an end when I said that history will reveal which came first in this chicken and egg argument: Did illegal immigration escalate when the courts ruled that America, instead of deporting immigrants, had to prevent employers from checking their immigration status, educate their children, give them full (as opposed to emergency) health care, and provide them with all welfare services? My bottom line was that, if those rulings sparked a huge uptick in illegal immigration, I am right, and the illegal immigrants are rational actors responding to American incentives. If one takes away those incentives one would dramatically decrease illegal immigration. Of course, if the statistic show the opposite — that the the ever increasing flow of benefits does not correlate to increased illegal immigration — my friend has a point, and I’ll have to revisit my theories.

The only problem is that I don’t quite know how to go about finding data matching welfare benefit outlays to the rate of illegal immigration. Google or Bing searches leave me inundated with information and I simply can’t process it all. Do any of you know of a single study or a single website that focuses on the long-term relationship between the freebies we offer and the flow across the border?

By the way, we did argue about myriad other immigration issues (mostly pure emotion versus rational sovereignty and economics), but he was really stuck on the fact that he believes they’ll come regardless of whether we make it easy or hard for them to be here, so that seemed like the best angle of education and attack.

Thanks for any help you can give.