They were criminals — thugs and thieves — a single ethnic group that filled the jails of big cities. “Scum unloaded on American wharves,” one speaker in Philadelphia said of them. Dirty, filthy, foreign. As for their children, they were “utterly ignorant of a place such as school,” The New York Herald reported.

Mexicans? No, the Irish of the 1850s, then pouring into Anglo-Saxon America at such a rate that it gave rise to a political party founded in opposition to immigration — the Know-Nothings. At one point, it was second largest party in the United States, complete with a paramilitary arm called the Wide Awakes.

Nearly 50 years later, as Italians and other southern Europeans left their barren lands for hope in America, a prominent educator and writer, Francis A. Walker, expressed a widely held view of these new arrivals: “They are beaten men from beaten races, representing the worst failures in the struggle for existence.”

Donald Trump — we’ve found your century. The xenophobes have always been with us, sometimes in power, usually not. It’s the mother of all ironies that a nation where all but about 2 percent (the Native Americans) of the population can trace its lineage to some distant land is now going through another of its anti-immigrant moments.