What's the maximum occupancy of the United States? I am sure you can't answer that because the question doesn't even make sense. There's no such thing as the maximum occupancy for geographical areas. So why is it that when it comes to immigration, some people act as if there's a maximum occupancy for the country.
I am not saying let's throw the border gates wide open and let everyone in. But you only have to go to Tijuana to see why immigration can never ever ever be enforced. If you live in abject poverty and you know that a better life is just minutes away (in fact, you can see that life outside your window), will anything prevent you from trying to make it across? Even if the penalty for illegal immigration is death, it'll still be more profitable to try. Because there's a chance, no matter how minuscule, that you will make it across. So spending billions of money on trying to keep people back is just an expensive exercise in futility. Building a fence would be laughable if it wasn't already been done with our tax money.
If we can't force them to stay out, what can we do? We do the same thing we normally do when govt wants to prop up an industry: we make illegal immigration unprofitable. If govt wants to stop people from smoking, they jack up the taxes on tobacco products. If govt wants to entice a developer to build, they give out tax breaks. You want people to invest, allow them to claim investment loses as tax deductions.
Alright fine, we get that but how do we do it? It's very simple: let everybody (except criminals) in! Let them in, remove the threats of illegality and put everything in the open. Right now it's profitable for companies to hire illegals because they can pay them less. What's the illegal going to do: complain to the authorities? No! So they get paid less; they mostly don't pay taxes and Uncle Sam doesn't get a cut. If you let everyone in (aka Guest Worker Program) and make it all legal, no illegal immigrant will work for peanuts. Uncle Sam can collect taxes from them and they are allowed to buy health insurance.
Talking about health insurance, unless we are prepared to allow people to die in the streets, we have to pay for health insurance for illegals. The question is do we pay on the cheap for prevention or pay dearly when people go to the ER for routine stuff. And if we decide to let them die in the streets, well you still gotta pick up the rotting bodies, don't ya? So one way or the way, people will get healthcare. So why not let them pay for it themselves by relaxing our immigration laws?
BTW, when I say "let them all in" I don't mean make them all citizens. You can be in this country legally and work without being on the "path to citizenship".