I have to call BS on your "honest research" comment. First of all, any articles that you would come across that you agree with, you would consider "honest," and any that print results that disagree with your preconceived notions, you would categorically view as "biased" or "unscientific." You are that guy.
Secondly, one of the definitions of "illegal immigrants" is the fact that govt and/or scientific agencies are not in contact with them, be it CBP, the INS, the IRS, or some research organization. I think the estimate that 12 million illegals are currently in the US is deliberately low. Considering that they show up in every state, even states nowhere near the border, it's probably double that.
I can attest that it's true that many states, including mine, do have a multitude of social programs that illegals can, and are even encouraged to take advantage of, whether we tax-payers like it or not. Why do you think people are so upset about "anchor babies," etc.? Now we are finding out that as soon as they enter, they are hooked up with housing, SNAP cards, job placement, Medicaid, the works. And it's not just Central Americans, either. There are a ton of Somalis and Middle Easterners currently milking our welfare system for all it's worth.
Being in the restaurant business, I have worked with all kinds of immigrants, legal, illegal, semi-legal, you name it. (When they "forget" to go back home after their visa expires) Sure, the majority of them take the sh** jobs that Americans don't want. And get paid sh** wages to do it. But for you to infer that that somehow makes it okay for them to be here, is ridiculous. It's still breaking the law, straining our limited national and state resources, and putting our security at risk.
We definitely need to get a grip on the problem. Would it cause a dip in the economy if all illegals were rounded up tomorrow and deported? More likely than not. No more cheap labor for the factory farms, the hotels, restaurants and sweat-shops. They would have to hire legal employees, which would drive costs up, at first. But eventually things would stabilize, and there would be a lot smaller incidence of workers being preyed upon. There is an enormous amount of financial, sexual and other predation happening to illegal immigrants, up to and including modern slavery, and they have no recourse whatsoever.
If we keep on doing what we're doing, nothing will change, nothing will get better. We, as a country, need to come together and come up with some real solutions. Personally, I think the Wall is a good start. Stemming the flow will keep things from getting worse, at least. And we need to use those social programs to not just keep them fed and housed, but to get them assimilated and self-reliant as quickly as possible. Compassion and practicality do not have to be mutually exclusive concepts. Indeed, for the US to move forward, it needs to utilize both.