This has nothing to do with employment. It has everything to do with bringing people in to replace the 50 million consumers we've killed off. Consumers need jobs and money to consume goods and services. We have increased our population by 115 million over the past 44 years. We have 68.5 million not holding a job. There is no shortage of labor.
I can't think of a single industry or government agency in the U.S. today that doesn't have a major financial interest in allowing millions of people to flood across our borders. And therein lies the problem, eh?
Motivated by parochial self-interest, the pro-mass immigration, open borders, amnesty advocates have formed a powerful coalition including the U.S. Chamber of Commerce, labor union leaders, the Catholic Church, ethnic and racial groups, “moderate” Republicans, and the Democrat Party. The common thread that unites these groups is power, money, and the prospect of increased constituencies, even at the expense of our long-term national interests and survival.
Keep in mind that the U.S. has the highest standard of living in the history of mankind right now. The natural tendency in this type of system is towards Keynesian economics fueled by consumer spending, debt financing and smoke & mirrors. Jobs aren't even necessary to keep the house of cards standing. Even with a very low labor participation rate, our capacity to produce far exceeds our ability to even consume what we produce.
Economic growth is fueled by: (1) population growth, and (2) productivity growth. For several decades we've been past the point where human productivity growth even matters anymore ... productivity growth is now almost entirely driven by automation and advances in technology and communications.
There's no doubt that the house of cards will eventually come crashing down, but that's not going to be driven by immigration (legal or otherwise).