Let’s not club legal and illegal immigration together.
I’m not sure if the above is factual. Following are the legal yearly immigration numbers.
Around 1 million Permanent residencies are awarded in USA per year.
Average 750K new naturalizations occur every year.
And on top of that
In 2012, 4.5 million U.S.-born children under 18 lived with at least one undocumented parent. That was 6.1 percent of the population under 18 – twice the percentage as in the year 2000.
Also, the argument of perpetual growth of human population while might be good for economics must also be examined from a non economic perspective (environment & non human species) [but that’s a separate issue & belongs to a different thread].