The nation’s falling fertility rate underlies many of our most difficult problems. Once a country’s fertility rate falls consistently below replacement, its age profile begins to shift. You get more old people than young people. And eventually, as the bloated cohort of old people dies off, population begins to contract. This dual problem—a population that is disproportionately old and shrinking overall—has enormous economic, political and cultural consequences.

For more than three decades, Chinese women have been subjected to their country’s brutal one-child policy. Those who try to have more children have been subjected to fines and forced abortions. Their houses have been razed and their husbands fired from their jobs. As a result, Chinese women have a fertility rate of 1.54. Here in America, white, college-educated women—a good proxy for the middle class—have a fertility rate of 1.6. America has its very own one-child policy. And we have chosen it for ourselves.

Forget the debt ceiling. Forget the fiscal cliff, the sequestration cliff and the entitlement cliff. Those are all just symptoms. What America really faces is a demographic cliff: The root cause of most of our problems is our declining fertility rate.

The fertility rate is the number of children an average woman bears over the course of her life. The replacement rate is 2.1. If the average woman has more children than that, population grows. Fewer, and it contracts. Today, America’s total fertility rate is 1.93, according to the latest figures from the Centers for Disease Control and Prevention; it hasn’t been above the replacement rate in a sustained way since the early 1970s.

The nation’s falling fertility rate underlies many of our most difficult problems. Once a country’s fertility rate falls consistently below replacement, its age profile begins to shift. You get more old people than young people. And eventually, as the bloated cohort of old people dies off, population begins to contract. This dual problem—a population that is disproportionately old and shrinking overall—has enormous economic, political and cultural consequences.

For two generations we’ve been lectured about the dangers of overpopulation. But the conventional wisdom on this issue is wrong, twice. First, global population growth is slowing to a halt and will begin to shrink within 60 years. Second, as the work of economists Esther Boserups and Julian Simon demonstrated, growing populations lead to increased innovation and conservation. Think about it: Since 1970, commodity prices have continued to fall and America’s environment has become much cleaner and more sustainable—even though our population has increased by more than 50%. Human ingenuity, it turns out, is the most precious resource.

Low-fertility societies don’t innovate because their incentives for consumption tilt overwhelmingly toward health care. They don’t invest aggressively because, with the average age skewing higher, capital shifts to preserving and extending life and then begins drawing down. They cannot sustain social-security programs because they don’t have enough workers to pay for the retirees. They cannot project power because they lack the money to pay for defense and the military-age manpower to serve in their armed forces.

There has been a great deal of political talk in recent years about whether America, once regarded as the shining city on a hill, is in decline. But decline isn’t about whether Democrats or Republicans hold power; it isn’t about political ideology at all. At its most basic, it’s about the sustainability of human capital. Whether Barack Obama or Mitt Romney took the oath of office last month, we would still be declining in the most important sense—demographically. It is what drives everything else.

If our fertility rate were higher—say 2.5, or even 2.2—many of our problems would be a lot more manageable. But our fertility rate isn’t going up any time soon. In fact, it’s probably heading lower. Much lower.

America’s fertility rate began falling almost as soon as the nation was founded. In 1800, the average white American woman had seven children. (The first reliable data on black fertility begin in the 1850s.) Since then, our fertility rate has floated consistently downward, with only one major moment of increase—the baby boom. In 1940, America’s fertility rate was already skirting the replacement level, but after the war it jumped and remained elevated for a generation. Then, beginning in 1970, it began to sink like a stone.

There’s a constellation of reasons for this decline: Middle-class wages began a long period of stagnation. College became a universal experience for most Americans, which not only pushed people into marrying later but made having children more expensive. Women began attending college in equal (and then greater) numbers than men. More important, women began branching out into careers beyond teaching and nursing. And the combination of the birth-control pill and the rise of cohabitation broke the iron triangle linking sex, marriage and childbearing.

This is only a partial list, and many of these developments are clearly positive. But even a social development that represents a net good can carry a serious cost.

By 1973, the U.S. was below the replacement rate, as was nearly every other Western country. Since then, the phenomenon of fertility collapse has spread around the globe: 97% of the world’s population now lives in countries where the fertility rate is falling.

If you want to see what happens to a country once it hurls itself off the demographic cliff, look at Japan, with a fertility rate of 1.3. In the 1980s, everyone assumed the Japanese were on a path to owning the world. But the country’s robust economic facade concealed a crumbling demographic structure.

Read More

Read an opinion article by Michael Barone on this topic here.