> By that logic we should restrict the number of children being born.
I disagree with this assertion. Controlling immigration is reasonable and proper when a nation state has boundaries, citizens vs non citizens, and an economic system to balance. Forcing people who want children to not have children is neither reasonable nor proper. With that said, we are in luck: the fertility rate is rapidly declining in almost every country [1], so this is not a problem we face. The future faces a worker shortage as the world ages rapidly, but we still must solve for today.
> But the growth of our country from a population of 50 million to 300 million did not result in a job loss of 250 million jobs.
To look at "jobs" in a vacuum is myopic. Are they good jobs? Do people need two or three jobs to survive? If not, we do not have enough good jobs, just jobs. We should be measuring someone's resulting quality of life from their economic activity, not the job(s). As I mentioned previously, if you cannot find domestic labor to perform a job at a market rate living wage, then perhaps immigration should be considered. We are at full employment and workers are still struggling to make ends meet. This does not call for more immigration; this calls for mechanisms to more rapidly push wages up.
Take construction jobs for example. At any time, there are about ~300k-400k construction jobs that are going unfilled due to lack of labor. Would those jobs be filled if domestic workers were trained and wages pushed up? Or would builders prefer to hire immigrants to do the work at wages on offer [2] [3]? The evidence shows the latter. There is a market clearing price for every job to be filled.
TLDR Maximize economic success for citizen workers, and then turn the knob on immigration accordingly.
[1] https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
[2] https://limos.engin.umich.edu/deitabase/2024/05/28/undocumen...
[3] https://eyeonhousing.org/2024/03/states-and-construction-tra...