Not everyone thinks this, but I know an extreme right-winger who thinks this. He is also a conspiracy theorist who thinks non-white people are out to get white people so, yeah, odd.
Not every immigrant is illegal or bad. I know a girl who didn’t speak English for 3 years when her family legally immigrated, so of course she’s been told this.
There was a 19th century political party that rose in opposition to the arrival of Irish Catholic immigrants. They had the audacity to call themselves the Native American Party. Also, known as the Know Nothings. They’re the gang that Bill the Butcher (Daniel Day Lewis) leads in Gangs of New York.