Answer
eventually returned to their home countries
Explanation
Many new immigrants entered in the US in the late 1800 in large numbers and most of them were from western and northern Europe. They fled to US because there was job shortage in their country and also crops farming failed due to their land being infertile and famine.There was also high taxation in their countries. Others were moving to US to seek for freedom due to the political and religion persecution. Many immigrants eventually returned to their home countries this is because in their mind they didn't come for a permanent stay.
I think this is the correct answer, but let me know if it is incorrect. People were having more children per family.
the longest one in history
Al-Qili is what I remember in my old history book.
