Gibbons, in his remarkable chronicle of the decline and fall of the Roman Empire, lists 5 major reasons while Rome collapsed.
On e of the 5 reasons was uncontrolled immigration. The Roman elites said, in effect, 'what the heck...come in if you want to." And, so they did...And, the 'immigrants kept their separate language, customs, religions,
customs and allegiances. The center could not hold..Pretty soon, there was not one Rome...there were 43 Romes. Easy pickings for the Barbarians who eventually crashed through the gates...When they crashed the gates, no on e was there to stop them.....Only one of the five reasons.....but we are following the immigration path to oblivion.....and, we have been doing it since 1985. Who is responsible???Both parties.....Different motivations, of course....Repub licans want the cheap labor...Democrats want the votes after giving the illegals every free thing on earth...