Africa and South America were colonized by the nations of Europe who then changed their plans and pulled out of the colonized countries. Today the mass migration against the routes of the colonizers should show one of the reasons colonization would have provided great benefits to the colonized cultures.
Donald Trump wants to stop the reverse colonization from changing the nature and character of America. He has an ambitious plan to close the border which will stop the re-colonization and to send the illegal immigrants back to where they came from or to someplace else. He is meeting with mass resistance from the America-haters who believe America should be punished.