Like all social change, population growth has costs (increased use of limited resources) and benefits (fresh ideas, more people to do necessary work). On the whole, history — both global and American — refutes the Malthusian belief that more people means more misery. To the contrary, a growing labor force is one factor that determines an economy’s capacity to grow. On that basis alone, it would be concerning that the Census Bureau has released new data showing that the U.S. population grew only 6.7 percent in the past decade, which is the slowest 10-year rate since the census began in 1790. Add that all living members of the baby boom generation will have turned 65 by 2030 — and that 18 percent of the nation will be at least that age, according to Pew Research Center population projections — and demographic stagnation begins to seem uncomfortably realistic.

The good news is that, even at reduced rates of growth, the U.S. population, 328.2 million, is still expanding more rapidly than populations of peer nations such as Japan (whose population of 126 million is actually shrinking). The bad news, though, is that both sources of the U.S. edge in population dynamism — a relatively strong birthrate and immigration — are implicated in the Census Bureau’s report. Net international migration — permanent moves to the United States minus permanent departures — was 595,348 between 2018 and 2019. In 2016, by contrast, the figure was 1,046,709. The Census Bureau and other experts have yet to identify a specific cause, but it’s certainly plausible to link the decline to the anti-immigration posture adopted by President Trump during that interval.

Meanwhile, the natural increase in the population between 2018 and 2019 — births minus deaths — was 956,674, the first reading under 1 million in “decades,” according to the Census Bureau. As of 2018, the United States’ total fertility rate stood at 1,728 births per 1,000 women over their lifetimes, well below the replacement rate of 2,100 births per 1,000 women. The causes are unknown, though there may be a continued hangover from the economic uncertainty of the Great Recession.

Unchecked, these trends may mean less economic growth and a diminished support base for a large retired cohort. Boosting birthrates, to be sure, is notoriously difficult, as a number of European countries and Japan have already discovered. Of course, compared with those other countries, the United States has done little to provide paid family leave or subsidized child care — and could do more.

Boosting immigration, by contrast, is relatively easy to accomplish. Or it would be, if the president and many in his party were not engaged in a simplistic campaign to demonize it, one result of which has been to slash refu­gee admissions from 85,000 in fiscal 2016 to 30,000 in fiscal 2019. Immigration should come through legal channels and be more closely tailored to fit labor force needs. But the need for more of it is real.

The recent dip in population growth need not prove irreversible. But the fact that starting a new life in the United States has come to seem less attractive, both to prospective parents already living here and to prospective arrivals from abroad, is a warning this country cannot afford to ignore.

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