"Demography is destiny in American politics." That was the first line of an article that Peter Brimelow and I wrote in the late 1990s: Electing a New People (National Review, June 16, 1997). We pointed out that, while voting patterns of the various races change very slowly, the county's demographic profile is shifting rapidly—because of immigration policy. In effect the federal government is electing a new, less Republican people. (For a 2001 update, see here).

Subsequent events have confirmed our thesis. The foreign-born population increased by nearly 50%—from 27.2 million in 1997 to 40 million today. Illegal aliens became the fastest growing segment of the foreign born population. Hispanics displaced Blacks as the largest U.S. minority.

Meanwhile, Black and Hispanic voters remain overwhelmingly Democratic.

But although immigration policy is the prime mover of demographic shift, the immigrants themselves are not. It is their U.S.-born children who account for most of it. In 2004, for example, immigrants, legal and illegal, accounted for 12% of the population—but 24% of total births.  

Over the long haul, children of immigrants are projected to be even more important: "Births in the United States will play a growing role in Hispanic and Asian population growth; as a result, a smaller proportion of both groups will be foreign-born in 2050 than is the case now." [Pew Research Center, U.S. Population Projections: 2005-2050, February 2008.]

Which brings us to the question Peter asked me to address in this article: what would be the impact of ending the birthright citizenship that is conferred by the current interpretation the 14^th Amendment on the future U.S. electorate?

Our quick and dirty calculation starts with this key fact: an estimated 380,000 anchor babies will be born to illegal alien mothers this year—an amazing 10% of all births in the U.S. These babies will become eligible to vote in 2028—a Presidential election year. If they all vote as Hispanics did in 2008 (namely, 67% Obama; 31% McCain), they will increase the Democratic total by a net 136,800.

Put another way, ending birthright citizenship today could benefit the Republican standard bearer by a net 136,800 in 2028 as a result of one year's births alone,

That may not look much. But it vital to grasp that the effect of the birthright citizenship loophole is cumulative. Thus the number of birthright Democrats born to illegals will compound rapidly after 2028—by the next Presidential election, 2032, they would be a net 547,000 advantage to the Democrats.

Of course, McCain lost in 2008 by 8.5 million votes. But many Presidential elections are much closer—for example, George W. Bush "triumphed" in 2004 by barely three million votes.

Moreover, the impact of ending birthright citizenship is not merely limited to the children of post-2010 illegals. Their grandchildren and great-grandchildren will not be citizens either—ad infinitum.

What will this add up to? The Census makes estimates of the total foreign-born population and the illegal alien population—about 40 million and 12 million, respectively. (Private estimates of the illegal population range up to 20 million). A crude way of expressing the rate at which illegal aliens have babies is to divide annual anchor births by the total (male and female) illegal alien population. Do the division—380,000/12.0 million—and you get 3.2%.

That is the "illegal alien birthrate". And it's is huge. The same calculation for Black non-Hispanics yields a 1.6% birthrate. For white non-Hispanics, 1.2%.

To assess the impact of closing the birthright citizenship loophole, we assume birth rates remains constant over time. And we also assume the illegal alien share of the foreign-born population will remain at its current level—30%—indefinitely. (This fraction actually rose for most of the period since the 1986 amnesty, but it may have stalled in the current recession.)

So would be the impact of ending birthright citizenship as of January 1, 2010 on the future U.S. electorate? The Republican vote?

Extrapolating from the Pew Hispanic Center's foreign-born population projections:

Between 2010 and 2050, we project 23.3 million anchor babies will be born to illegal aliens in the U.S. Somewhere less than half of them —11.0 million—will be of voting age in 2050. We estimate they will raise the Democratic vote by 4 million net.

Fast forward to 2100. By then, 80.7 million post-2010 anchor babies will have been born. Some 55 million of them will be of voting age. If they all vote, the Democratic vote margin will increase by 19.8 million net.

By comparison, the largest popular vote margin of victory in U.S. history was 16.9 million, when Reagan beat Mondale in 1984.

Next: anchor grandchildren. We assume that (a) half of anchor babies are female; and (b) their fertility rate equals that of Mexican women living in the United States (3.51 children per mother over her childbearing years, 18 to 45.)

By 2050, some 4.6 million anchor grandchildren will have been born to female anchors. Only 219,000 will be of voting age that year. But by 2100, the grandkid contingent swells to 51.8 million—of which 29.6 million will be of voting age.

If they vote like Hispanics did in 2008, the Democratic vote will increase by another 10.7 million net.

(We haven't said anything about male anchor babies. Our implicit simplifying assumption is that they are the fathers of the anchor grandchildren. If, however, they father children outside the anchor baby community, they could tack on another 21.4 million to the Democratic majority in 2100—that is, if both parents were required to be legal residents, the potential impact of ending birthright citizenship on the grand-kid electorate could double.)

Bottom line: unless the birthright citizenship loophole is reformed, it could increase the Democratic popular vote by 41.2 million net in 2100, when the total electorate will number 480 million.

More than half of that, or 21.4 million, will be due to the anchor grandchildren born after 2010.

Of course, the effect will be concentrated in the immigration-impacted states. For example, an estimated 117,000 anchor babies were born in 2002 in California, probably a third of the total for the entire U.S.

Oh, and by the way—none of this counts the great-grandchildren of illegal immigrants, of whom there will be probably 2.0 to 2.3 million in 2100.

Needless to say, in this back-of the-envelope calculation we've made heroic (albeit entirely reasonable) assumptions. Our challenge to critics: go make your own calculations.

In fact, why haven't you done it already?

Bottom line: ending birthright citizenship could slow the immigration-driven drift to disaster of the GOP (a.k.a. the party of the historic American nation)) by as much as half.

No wonder the proposal is provoking such hysteria.

Edwin S. Rubenstein (email him) is President of ESR Research Economic Consultants in Indianapolis.