Local < 2 fertility rates are swamped by global > 2 rates. Overpopulation is a global problem affecting the US, same as global warming. The US is fast growing in population.
As for being swamped, lately, in spite of the recent economic downturn, global population growth rates have been lessening by more than demographers expected. All of this can be read with a cursory Google search. My numbers are from the UN, US Census Dept., and Pew Research.
And yet media reports consistently imply that restricting immigration is both impossible and unethical.
That's fast growing to me.
No.
Google: 'US births per woman'. In the US, that is ~1.7. 2.1 is considered the replacement rate in developed countries.
After that, check out: 'world births per woman' Currently (2011) @ 2.41 down from 2.67 in 2000, 3.23 in 1990. Do you expect this trend to suddenly flatten or reverse?
In the future, longer life expectancy will likely have a larger impact on population numbers than birth rates. In specific developed countries, I would also expect immigration to be part a large part of growth.
Global average population growth rate is 1.1%.
[1] http://www.pewhispanic.org/files/2005/09/2005-immigration-tr...