I'm against illegal aliens being allowed into the country, any country, for obvious reasons. I realize that the majority of them, probably the vast majority, that come into this country at least, are good, hard-working people who just want to make money and/or raise a family in the U.S. Despite this, it's against the law obviously and at least a small percentage of them are criminals, potentially serious offenders.

That being said, I would also have assumed that another downside was that they take more than they give back, financially, but according to some government official (who I'm sure is at least smarter, and better educated than myself) here in NE, they actually put more money into the system, relative to what they take away from it, compared with the average legal resident. That's in this state at least.
edit: I'm not sure "financially" is the right term there, but hopefully you get the gist of what I meant.

I'd assume they do, however, put a strain on our school systems as a result of being here, undocumented, and birthing children once in this country. I don't know for a fact if that's true though.

However, if they're already over here, speak English or at least make a real attempt at learning it so they can communicate to someone who speaks only English, pay taxes(once they become legal, or even before, if that even works h, have very few if not zero children, and just go to work like the rest of us without committing crimes, then they're fine by me.