We’re becoming Europe. At least, that’s what a long line of U.S. birth-rate figures seems to being telling us. And that’s bad news for the future of the country.

New numbers released by the U.S. government on Tuesday show record-low birth rates in 2011: the general fertility rate (63.2 per 1,000 women ages 15 to 44) was the lowest ever recorded; the birth rate for teenagers ages 15 to 19 declined; birth rates for women ages 20 to 24 hit a record low; and rates for Hispanic and non-Hispanic black women dipped. Some birth rates remained unchanged, like those of women in their late 40s. Only women ages 35 to 39 and 40 to 44 are more likely to have babies now than in the past…

The U.S. rate hasn’t fallen to European levels yet. The birth rate of children per woman in the U.S. is about 1.9. But the downward trend will almost certainly force the U.S. to rethink how to financially support the elderly and fund programs like Social Security and Medicare, ongoing economic debates that will take on even more weight as the country ages.

The first part of the story is the fertility rate by age. The fertility rate for women in their 30s and older remained basically constant—the Great Recession hasn’t stopped older women from having children. The big declines have come among women in their 20s. This trend of delaying childbirth is perfectly consistent with what we’ve seen in America since the late 1960s: As more people began attending college (and then graduate school), the average age of first marriage rose. As women (and men) waited longer to get married, they waited longer to have children, too. So the average age of women’s first birth rose in tandem…

[B]uried deep in the report is the most telling number of all: In the last year the number of “first” births dropped to the lowest level ever recorded in America. What does that mean? It means that we’re slowly bifurcating into a country where there are two kinds of adults: people who have children, and people who do not. The people who have children are inclined to have seconds and thirds. But for the first time in our nation’s history, we’re growing a sizable cohort of adults who remain childless their entire lives.

And a sea change like that never happens without consequences.

What the entitlement state meant was that for the first time in history, people didn’t need children to care for them in their old age. The government would do it. Socializing this cost created a market distortion. Children are expensive to raise and everybody gets the government’s geezer goodies, whether they pay for the cost of creating new taxpayers or not. So only the suckers have kids.

That’s the economic argument. And I don’t mean to dismiss it, because it has been an important driver in what’s happened to fertility in America. But as to the specific question we’re looking at today—the rise of childless Americans in the last 40 years—it just isn’t sufficient to explain the shift. After all, by 1970, Social Security had been on the books for a generation. And when you look at our fertility numbers, they’d been trending slightly downward since 1950 as the Baby Boom faded. But just around 1970, they went into a nosedive.

Which brings us to the second explanation: It’s the culture. What happened beginning in 1970 was a massive change in American culture. Just to tick off a few of the most obvious changes: abortion, contraception, marriage, divorce, and religious practice. Each of these subjects underwent titanic shifts beginning in or about 1970. And as our relationship to them changed, so did our behavior with regards to family life.

Where does that leave us today? With one final, scary thought. What if our new reality—the fact that a fifth of Americans no longer bother to have children at all—exerts its own pull on our demographics? There’s some data from Europe and the Far East to suggest that once a critical mass of people choose to remain childless, their example influences young adults and alters their behaviors and expectations.

The emerging “new politics” of the rising Single Nation could impact elections for decades to come, particularly in Democratic strongholds like Chicago, New York or San Francisco. These areas will be increasingly dominated by a vast, often well-educated and affluent class of voters whose interests are largely defined around their own world-view, without overmuch concern with the fate of offspring, along with the urban poor and the public workers who tend to both groups. Since the childless frequently lack the kinship networks that are obliged to provide for them in moments of trouble, they tend to look more to government to care for them in hard times or old age.

But the Single Nation’s grip on power may not be sustainable for more than a generation. After all they, by definition, will have no heirs. This, notes author Eric Kauffman, hands the long-term advantage to generally more conservative family-oriented households, who often have two or more offspring. Birth rates among such conservative populations such as Mormons and evangelical Christians tend to be twice as high than those of the nonreligious.

As a result, Kauffman predicts that inevitably “the religious will inherit the earth” and ensure that conservative, more familial-oriented values inevitably prevail. Even among generally liberal groups like Jews, the orthodox and affiliated are vastly out-birthing their secular counterparts; by some estimates roughly two in five New York Jews is orthodox, including three quarters of the city’s Jewish children. If these trends continue, politics even in the progressive nirvana of Gotham may be pulled somewhat to the right.

Using charts and info from Pew, the Census, and a Ph.D presentation put together by Elise Barrella & Sara Beck of Georgia Tech, we’ve found some interesting facts about what America will look like in a few decades…

These evolving demographic dynamics will have consequences on the economy, which we also address in this feature.