A new projection reckons that this year, for the first time in history, the number of Americans could decline. That marks a sobering development for anyone concerned about the future of the republic. After all, this nation’s greatest source of prosperity and power are the American people themselves. A decline in the number of Americans plots a course for a weaker, poorer country in the decades ahead.

The potential population drop comes from the American Enterprise Institute. It points to the fact that “immigration numbers and birth rates have plummeted,” the New York Post reports. Net migration to America could fall this year, AEI says, with 525,000 fewer people entering than leaving. Plus, too, the number of births compared to deaths will add just 519,000 people to the population. That means 6,000 fewer Americans. 

It amounts to “the first population decline in nearly 250 years of American history,” per the Post. This is unprecedented in the nation’s history, since “the US population has always increased every year, even if not significantly,” the Post adds. That growth has held even in the sanguinary years of the Civil War, when more than 600,000 Americans perished. Nor, during the Covid pandemic, did the population flag.  

The overall population dip, if it plays out as AEI foresees, could be seen as the other shoe to drop after the news that the number of immigrants living in America is, for the first time in decades, falling. That demographic development is “a whiplash-inducing turn of events,” these columns reported. For it comes “on the heels of the Biden administration, during which we saw the largest wave of migration in American history.”

In the Times’s telling, the decline in America’s immigrant population was historic, because the last time the country “experienced negative net immigration” was “in the 1930s, during the Great Depression.” The fall in the number of foreign-born residents here, though, has yet to be met with a corresponding increase in the native birthrate, hence the potential decline in the national head count. 

It’s hard to avoid the sense that a fall in the nation’s population is a symptom of, well, decline. If America’s history is any guide, a soaring population is synonymous with the fulfillment of the nation’s potential. That point is underscored by the author of the book “One Billion Americans.” Matthew Yglesias reckons that America is underpopulated and that the nation should be aiming for a near-tripling of its current population.

Mr. Yglesias’s book sees a stagnant population as a signal “that America has lost the will and the means to lead.” He avers that to “compete with the huge population clusters of the global marketplace,” more Americans are needed via more births, more migration, or both. Yet this vision stands in contrast with the fashionable leftists, fretting over ecological implications, in thrall to so-called “anti-natalism,” meaning the refusal to have children. 

As America’s 250th birthday nears, the prospect of a population plunge sends a sour signal. In 1801 Jefferson, reporting on the second census, marveled at America’s soaring population. “We contemplate this rapid growth, and the prospect it holds up to us,” he said, as a harbinger of “the multiplications of men susceptible of happiness, educated in the love of order, habituated to self-government, and value its blessings above all price.”