This is the redoubtable Ann Coulter referencing Peter Brimelow's Time To Rethink Immigration in WND:

Historically, immigration has helped America – why is it now hurting our country?

That’s nonsense!

1) As Peter Brimelow points out ALL NATIONS ARE NATIONS OF IMMIGRANTS. STOP CALLING AMERICA “A NATION OF IMMIGRANTS!” Do people imagine the British simply emerged from the mud as proper, common law-respecting, tea-drinking Englishmen? The Romans occupied it, the Normans invaded, Germanic tribes replaced the Normans, the Vikings invaded and a thousand of years later, the Muslims came and wrecked the place. I may have gotten some of the invasions mixed up, but that’s it in a nutshell.

2) As Milton Friedman has said: You can’t have open borders and a welfare state. For roughly the first three centuries of America’s existence, anyone could come here – and good luck to them! If they couldn’t make it, they went home. About 30 percent did. We skimmed the cream of the world! By the time of the American Revolution, this had created something distinctive about Americans, as described absolutely beautifully by Alexis de Tocqueville’s “Democracy in America.”

Even after the Democrats ginned up the welfare machinery, the country maintained the same national character and stayed largely the same demographically because our immigration policy imposed quotas to replicate the nationalities of the people already here. But in 1965, Teddy Kennedy’s immigration act intentionally changed the ethnicity of immigrants to favor those from the Third World and freeze out people from countries that had traditionally sent us our immigrants. Since the late 1970s, more than 90 percent of the immigrants to America have been from the Third World. This has led to wider income inequality, a higher crime rate, more unemployment and on and on and on. The 1965 immigration act was the worst thing that ever happened to this country.

WND EXCLUSIVE | ANN COULTER: U.S. 'FINISHED' IF AMNESTY PASSES

'There will be no point in fighting for anything anymore'

By Garth Kant, WND, June 18, 2013

In 1992, Peter Brimelow wrote

'"We are a nation of immigrants." No discussion of U.S. immigration policy gets far without someone making this helpful remark. As an immigrant myself, I always pause respectfully. You never know. Maybe this is what they're taught to chant in schools nowadays, a sort of multicultural Pledge of Allegiance.

But it secretly amuses me. Do they really think other nations sprouted up out of the ground? ("Autochthonous" is the classical Greek word.) The truth is that all nations are nations of immigrants. But the process is usually so slow and historic that people overlook it...

This is obvious in the case of the British Isles, from which the largest single proportion of Americans are still derived. You can see it in the place-names. Within a few miles of my parents' home in the north of England, the names are Roman (Chester, derived from the Latin for camp), Saxon (anything ending in -ton, town, like Oxton), Viking (-by, farm, like Irby), and Norman French (Delamere).

As Ann says, most of that was invasion, rather than immigration.