We're not a nation of immigrants, really. We're a nation of conquerors and colonists.
Immigrants came later. The first few million stood on the shoulders of the conqueror-colonists and reached higher. In these latter years, immigrants (mostly the illegal ones) seem content to get on the shoulders of the (now-)natives...and sit and whine about the meanies who are holding them up.
Time to shrug...
I say this as a descendant of immigrants, the earliest known of whom landed in the existing colony of New York (conquered and colonized by the Dutch, then conquered by the British), immediately set about farming, and became progenitor of others who fought for independence, international recognition, and freedom inside and outside the US (War of Independence, 1812, Civil War, WW2, Persian Gulf I) while pursuing peacetime occupations of farming, construction, manufacturing and business.