Trump's loud and calculated rhetoric aside, is there any scientific data on how many people can reside in the United States without straining its resources past the manageable limit? The reason I ask is this: I don't know.
In terms of arable land and minerals, how many is too many? Do we have enough to sustain 400 million? A billion? Two billion?
I have heard two theories on this (but no scientific data to support either):
There's plenty of everything. It's not a question of running out of resources: rather, it's about limiting the appetites of the corrupt money-grubbers and schemers.
Soil corrosion and various damage to the environment are the results of overpopulation. There are already too many people here, and if immigration continues at today's rates, we'll soon be a Third World country.
I don't know if either of these theories has any validity, and I'd like to see some numbers, but apart from that, has the question of limiting immigration because there may not be much room left in the country been raised by a big-name politician?