Some time back, I got into a discussion with some commenters on Open Borders. The starting point was a claim by Peter Brimelow who is the editor of the restrictionist website VDARE. In an address to the Philadelphia Society, delivered in 2006, he stated it this way:

„But the last estimate that I saw, when I was researching Alien Nation, was that if there had been no immigration at all after 1790—none at all—the population of the US would still be about half of what it is now, through natural increase.“

This is part of an argument that it is misleading to call the US a “nation of immigrants.”

I was baffled by the claim, and my first reaction was to point out that American population would have grown by a factor of 40 since 1790, while the population of Germany grew only by a factor of less than 4, and world population by a factor of 7. A commenter then supplied an argument that very high fertility in the early US was behind it. This seemed to be an explanation, and so I retracted my criticism, but was still amazed how that could be.

Turns out I gave in too fast because:

The US really is a nation of immigrants, and overwhelmingly so.

I will go into more detail in another post because there are further aspects that are interesting (hint: it’s the momentum effect again). Here I will confine myself to a simple argument that shows why something has to be wrong with Peter Brimelow’s claim. I will also derive a more realistic estimate for the counterfactual.

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Let’s first look at where the US population in 1790 had come from: Of the slightly more than 3.9 million inhabitants, about 760,000 were African Americans, mostly slaves. Native Americans were not counted at the time. The rest were of European descent, some 3.2 million people. More than 2.5 million of those of European descent or 78.6% traced their ancestry to Britain (59.7% English, 10.1% Scots-Irish, 5.0% Scottish, and 3.8% Welsh).

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The reference year for Peter Brimelow’s claim is 1990, and he asserts that about half of the American population would have been there at that time without any immigration after 1790: 122 million in the counterfactual versus an actual population of 249 million (cf. “Alien Nation – Common Sense About America’s Immigration Disaster”, page 48).

There were 30 million African Americans in 1990. It is certainly an overestimate that all of them would have been there without any immigration after 1790 where this would have to include also forced “immigration.” That’s so because about half of all new slaves were brought to the US after the founding of the Republic.

Let’s be generous and concede 20 million African Americans in the counterfactual. There were also almost 9 million Native Americans who would have been there in 1990. So the number of all those of European descent in the counterfactual works out as 122-20-9 = 93 million people in 1990.

It is reasonable to assume that 78.6% of those 93 million would have been of British descent in the counterfactual, or about 73 million people. Otherwise you would have to explain why other groups (mostly Germans, Dutch, French, and Irish) had vastly diverging fertility over 200 years. I don’t see how you can make that case.

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Now, since the counterfactual is just a part of what really happened with immigration, there should have been also at least 73 million actual people of British descent in 1990, or about 29% of the population. Of course, those would only be the same people as in the counterfactual if there had been complete segregation of later immigrants, which was not the case.

What counts here are surnames which anchor a claim to ancestry. Since half of someone’s descendents (usually sons) keep the surname, and half of them (usually daughters) lose it, the shares do not change a lot across generations. That is barring strongly differential fertility or systematic name changes that I find implausible. So the shares for ancestries should be roughly stable.

But then 29% has to be an underestimate because there were another 3.5 million immigrants from the UK between 1820 and 1930 alone. You can get a rough idea from German immigration for the effect of that later immigration in 1990.

There were only 280,000 Americans of German descent in 1790. They should have grown to about 7 million people in 1990 with the same rate as for those of British decent. But there were another 5 million German immigrants between 1850 and 1930. In 1990, there were 58 million Americans of German descent. So the 5 million later German immigrants should have grown to about 51 million people.

Hence it seems reasonable that the 3.5 million later British immigrants from 1820 to 1930 should have grown to some 35 million people. But that means that the share of those of British descent in 1990 would have been about 43% of the total population (108 million out of 249 million).

However, there were only 18.8% in 1990 who claimed to be of British descent or much less than half of what it should have been if Peter Brimelow were right.

There is one objection, though. There were also 6.2% who declared “American”, “US”, “European”, or “white” ancestry in the 1990 census. Probably some of them should be counted as of British descent, too. But even if you include all of them, you only get to 25%, or somewhat more than half of what is required. So the numbers simply don’t add up for Peter Brimelow’s claim, and that is so by a wide margin.

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Now let’s derive a more realistic estimate (which has its limitations, but should be much closer to the truth):

If you take the high estimate of 25% for those of British descent (including all those who checked “American” ancestry, “US” ancestry, and so forth), there were about 62 million people in 1990 that belonged to that group. Subtracting the 35 million resulting from immigration after 1790, yields 27 million people, or only somewhat more than a third of the 73 million in the counterfactual.

But that can only mean that also the number of those of European descent in the counterfactual has to be much lower, not 93 million, but only 34 million people. Add in the 20 million African Americans (probably an overestimate) and the 9 million Native Americans, and you arrive at an estimate for the American population in the counterfactual of 34+20+9 = 63 million people.

Hey, that’s not bad, that’s almost the population of France! It is well below that for Germany, though, and only half the Japanese population. But relax, the US would still be more populous than Canada, admittedly not by a lot.

And a population of 63 million people would have been only 25%, and not almost 50% of actual population in 1990. Or in other words: Roughly 75% of the American population were there because of immigration after 1790!

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But there is also a silver lining for Peter Brimelow here: The US was taken over by immigrants long ago, and it worked out so well that he is now defending the result as the status quo. Just imagine: No one would have noticed this massive swamping if I hadn’t written my post. And it is a fine example of how a nation of immigrants could become a great country. Make America great again!