Depopulation — unremitting, long-term population decline — promises to be the 21st century’s most important demographic trend.

After centuries of seemingly unstoppable increase, world population is on track to peak soon.

The United Nations’ latest projections envision depopulation starting as soon as 2052 — just a generation hence.

Depopulation is no future fantasy. A growing number of countries are in prolonged population decline.

China, Japan, South Korea, Taiwan — all already depopulators, as are Russia and eight of the European Union 27.

By UN estimates, in fact, more than 50 countries and territories around the world had fewer births than deaths in 2023.

For such “net mortality” societies, only immigration can prevent national-population shrinkage.

Once upon a time, depopulation would have been unthinkable for the United States.

No longer. And it could happen much faster than almost anyone realizes.

The demographic engines that have powered America’s amazing economic and geopolitical ascent since 1776 — fertility and immigration — are faltering today.

Let’s look at both, starting with fertility — the foundation of every country’s demographic outlook.

Throughout our history, American birth rates have been exceptionally high for a rich nation. In colonial times, total fertility was about 7 births per woman; Benjamin Franklin likened our frontiersmen to “locusts swarming across the countryside.”

More recently — over the postwar era’s past three generations — US fertility levels averaged 20% above Europe’s and 30% above Japan’s.

But falling birth rates pushed developed countries’ fertility below the replacement level 50 years ago — including America’s.

In the years since 1972, US annual fertility rates only hit replacement twice.

For most of this period (1972 to 2007) American childbearing was only just barely below replacement.

But in 2008 it started to slide, and by the early 2020s it was more than 20% below the roughly 2.1 births per woman required for long-term population stability.

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