It seems very simple to me

Theres a big statue in New York Harbor with a poem on it.
It doesn't say anything about quotas or qualifications or skills. Waves of immigrants have "overrun" this country over the past two centuries and every one of them has made this nation stronger and better, whether they were doctors or ditch diggers.
Currently our corporations rely on an underclass of illegals to provide labor at the lowest possible rate. They can do that because these people are kept illegal. If they were legal residents, they would have to be paid legal wages. That would raise the floor of labor compensation across the board. Big money don't want that.
So, as they always have in the past, they stir up the racial divide, they talk about Our White Christian Heritage Bullsh!t, our racial purity. And it works! And people who won't even admit it to themselves fall for it. In a stratified hierarchy, somebody's got to be the bottom. The more stratified, the more wretched the bottom is.
Ever stop to think why 12 million people would leave their homes and families, brave harsh conditions and dangerous people to sneak into America and take backbreaking jobs for pittance? Think it has anything to do with NAFTA? or the Maquiadoras that pay 1/10 what they pay up north? For a century, we've exploited Central America ruthlessly, meddling in their governments, leaving their economies in shambles, NAFTA was just the icing on the cake. Not that our corporations are sweetness and light to US, but they don't give a crap about the brown people they squish in those "backward" countries.
And neither do many Americans.
Our borders don't contain the flows of money and power in the world. They hardly guage the flow of goods. The only thing they stop is people and they don't do a very good job of that. And we need those people. With 12 million undocumented workers and low unemployment, it would seem that their absence would put a crimp in the businesses that they work for.
The only honest immigration reform is to open the borders to all comers, it's an American tradition. Or did y'all forget about:
"Give me your tired, your poor,
Your huddled masses yearning to breathe free,
The wretched refuse of your teeming shore.
Send these, the homeless, tempest-tost to me,
I lift my lamp beside the golden door!"
We're all immigrants on this continent.