"Those who cannot remember the past are condemned to repeat it."

Beginning very early on in the history of the United States, immigrants have been regarded as somehow "other," and inferior, possibly not fully human. Look at the response to the Irish immigration (late 1840s/early 1850s), which was a consequence of the potato famine. (The "know-nothing" party was maybe the clearest manifestation of this:
https://en.wikipedia.org/wiki/Know_Nothing)

Later, as immigration from eastern (Poland; Russia--many of these immigrants were also Jewish) Europe, southern Europe (Italy. Greece), and Asia (especially, but not only, China), anti-immigrant sentiments shifted. Chinese immigration was *legally prohibited* beginning in 1882 (https://en.wikipedia.org/wiki/Chinese_Exclusion_Act).
(Read the whole thing...)

And a discussions of the response to European immigration. (https://herb.ashp.cuny.edu/items/show/513)

Eastern and southern immigration:
"Between 1880 and 1910, almost fifteen million immigrants entered the United States, a number which dwarfed immigration figures for previous periods. Unlike earlier nineteenth century immigration, which consisted primarily of immigrants from Northern Europe, the bulk of the new arrivals hailed mainly from Southern and Eastern Europe. These included more than two and half million Italians and approximately two million Jews from Russia and Eastern Europe, as well as many Poles, Hungarians, Austrians, Greeks, and others.
"The new immigrants’ ethnic, cultural, and religious differences from both earlier immigrants and the native-born population led to widespread assertions that they were unfit for either labor or American citizenship. A growing chorus of voices sought legislative restrictions on immigration. Often the most vocal proponents of such restrictions were labor groups (many of whose members were descended from previous generations of Irish and German immigrants), who feared competition from so-called “pauper labor.” "
Note the opposition of earlier German immigrants to the immigration of Italians, Greeks, Poles, Russians (and especially Jews).

IQ tests were used (and, I think, developed) as a tool to restrict immigration in the early 1900s:
"Low test scores (given as an intelligence quotient, or IQ) were used by eugenicists to lobby in the US Congress for restricting immigration of those claimed to be genetically inferior in IQ."
https://www.researchgate.net/…/230435620_Intelligence_Tests…
And, as this articles in the Smithsonian puts it:
"This Jigsaw Puzzle Was Given to Ellis Island Immigrants to Test
https://www.smithsonianmag.com/…/puzzle-given-ellis-island…/

Famously, Jews attempting to flee the Nazis were denied entry to the US in the 1930s; the Dominican Republic, unlike the US did admit them:
"In the end, only one country, the Dominican Republic, officially agreed to accept refugees from Europe. (Dictator Rafael Trujillo, influenced by the international eugenics movement, believed that Jews would improve the “racial qualities” of the Dominican population.)"
https://www.facinghistory.org/defying…/america-and-holocaust

While the response to the "boat people" from Viet Nam was somewhat more restrained (in terms of official immigration policy--perhaps in part because so many were children of US military personnel), they were not warmly welcomed in a lot of US communities, especially along the Gulf coast.
https://en.wikipedia.org/wiki/Vietnamese_boat_people
and
https://www.jstor.org/stable/2545339…
(In my opinion, the response to the plight of Vietnamese refugees was particularly unfortunate, because the US was largely responsible for the conditions that led them to flee their homes.)

So what we are facing today is not anything new. In all--or almost all (we have not really escaped our reluctance to allow immigrants from Latin America)--the previous cases, attitudes changed; groups that were excluded or stigmatized (especially the Chinese) became desirable.

It's almost as if we don't want to remember our past, and, we refuse to remember it, and we keep making the same mistakes over and over again. Or, as George Santayana put it more eloquently:

"Fanaticism consists in redoubling your efforts when you have forgotten your aim... Those who cannot remember the past are condemned to repeat it."