America's first great replacement suffered—against the successful, individualistic WASP population—involved millions of non-Northwestern Europeans, unassimilable classes whose habits were less civil, minds less complex, dreams less meaningful.

Stemming this tide insufficiently has permanently altered America's destiny. Nevertheless, much to learn from the 1882-1924 immigration measures.
Firstmost, assimilation as virtue is virtually unpossible, applying to a select few, best done with close or complementary ethnics.

Assimilation's easiest mechanism is intermarriage, otherwise clans appear, but some groups simply can't mix. In America, British and NWE immigrants intermarried with native stock significantly—South & East Euros, etc. less so. All groups match the same in once homogenous Australia.

Secondly, migrant prevention is merely a reassurance. We must advocate reduction of whomever is unfit, those harder to remove, plus return of the unwanted, many of whom may claim root or consider their role useful.