Third: The Federal Reserve has reported labor shortages in multiple industries throughout the country. That inhibits business growth. Nor are the shortages only a matter of missing “skills”: The New American Economy think tank estimates that the number of farm workers fell by 20 percent between 2002 and 2014, accounting for $3 billion a year in revenue losses.

Fourth: Much of rural or small-town America is emptying out. In hundreds of rural counties, more people are dying than are being born, according to the Department of Agriculture. The same Trumpian conservatives who claim to want to save the American heartland from the fabled Latin American Horde are guaranteeing conditions that over time will turn the heartland into a wasteland.

Fifth: The immigrant share (including the undocumented) of the U.S. population is not especially large: About 13.5 percent, high by recent history but below its late 19th century peak of 14.8 percent. In Israel, the share is 22.6 percent; in Australia, 27.7 percent, according to O.E.C.D. data, another indicator of the powerful correlation between high levels of immigration and sustained economic dynamism.

Finally, immigrants — legal or otherwise — make better citizens than native-born Americans. More entrepreneurial. More church-going. Less likely to have kids out of wedlock. Far less likely to commit crime. These are the kind of attributes Republicans claim to admire.

Or at least they used to, before they became the party of Trump — of his nativism, demagoguery, and penchant for capricious cruelty. It was nice to hear Republican legislators decry the family separation policy. But there’s no sugarcoating the fact that a plurality of Republicans, 46 percent, favored it, while only 32 percent were opposed, according to an Ipsos poll commissioned by the Daily Beast.

This isn’t a party that’s merely losing its policy bearings. It’s one that’s losing its moral sense. If anti-Semitism is the socialism of fools, then opposition to immigration is the conservatism of morons. It mistakes identity for virtue, entitlement for merit, geographic place for moral value. In a nation of immigrants, it’s un-American.

I’ll be accused of wanting open borders. Subtract terrorists, criminals, violent fanatics and political extremists from the mix, and I plead guilty to wanting more-open borders. Come on in. There’s more than enough room in this broad and fruitful land of the free.