Originally Posted by
bae
I suppose that all depends on what "large" is. 433 million people live in South America, 181 million in Central America, and 127 million in Mexico. 742 million people.
There were 1 million immigrants from Ireland from 1820 to 1845, at a time when the population of Ireland was about 7.5 million (average weighted handwave, note I stopped just as the Potato Famine data starts). 13.3% of the population. 1 million over 25 years.
Say 13.3% of the 742 million people South of us decide to freely move here. ~99 million people, over 25 years. The population of the USA today is 328 million people. The projected population of the USA in 25 years, not assuming this immigration, is 388 million.
So the new immigrants would add 99 million to that projected population, for a population of 487 million, and they would be 20.3% of the population.