Some supporters of President Donald Trump argue that his restrictionist agenda only targets illegal immigration, but that idea has now been decisively disproven. Many of the Central Americans now being detained by the Trump administration are legally seeking asylum rather than people trying to enter the country without permission. But during a recent briefing, the president declared:

Our country is full. Our area is full. The sector is full … Can’t take you anymore. I’m sorry, turn around, that’s the way it is.

The president’s actions show that he’s serious. He has initiated a purge of officials in the Department of Homeland Security whom he perceives to be insufficiently tough on immigrants, and said that hardline adviser Stephen Miller is now “in charge” of immigration policy. That could indicate that Trump is planning to renew his contentious family separation policy, close the Mexican border, try to curtail birthright citizenship or enact any other number of harsh nativist policies.

But what about Trump’s central contention that the U.S. is “full”? Is that true? Although there’s no widely accepted definition of what it means for a country to be full, the answer is probably no.

First, although the U.S. has a higher population density than Canada or Australia, it is still sparsely populated compared to most other developed countries:

Of course, population density by itself doesn’t really tell whether a country can accommodate more people. Much of Canada and Russia, for example, is not ideal for human habitation (though global warming may change this). Australia, meanwhile, doesn’t have much land for growing crops.

The U.S., in contrast, has plenty of land available for farming — 16.6 percent, compared to 12.7 percent in China, a country with four times the population and about the same land area. Thanks to its natural bounty, the U.S. is one of the world’s top food producers, and easily the world’s leading food exporter. It would have no trouble feeding a much larger population.

An equally important natural resource is water, especially as climate change begins to bite. Here the U.S. again comes out looking better than most other developed countries:

And of course, with recent advances in hydraulic fracturing, the U.S. is self-sufficient in energy too.

So in terms of space and natural resources, the U.S. is far from full. Many states, such as New York, Illinois, Connecticut and Louisiana, are actually losing population. A number of metropolitan areas, including those surrounding Chicago, Detroit, Baltimore and St. Louis, are losing people as well.

The U.S. population is still growing, but the rate is slowing — 0.62 percent in 2018, about half the rate of the 1990s. Part of this is due to the end of mass immigration from Mexico, but part is due to a fall in the U.S. fertility rate:

The U.S. fertility rate, at 1.8 children per woman, is now well below the 2.1 needed for long-term population stability. In other words, without continued immigration, the U.S. population will peak and decline. What’s more, the drop in fertility looks like it’s not just a temporary response to the economic hardship of the Great Recession, but a structural shift. Hispanic fertility has converged with white and black sub-replacement levels:

Economist Lyman Stone predicts that the fertility rate will fall even further, to 1.5 or even 1.4. That would put the U.S. in the same situation as countries like Japan, where a rapidly aging population places an increasing burden on the young and decreases companies’ desire to invest domestically.

So rather than being full, many parts of the U.S. are in danger of emptying out. But paradoxically, some cities in the U.S. actually do look like they’re getting full. These are the superstar cities — New York City, Los Angeles, San Francisco and a handful of others — where knowledge industries have been clustering in recent years, bringing in an influx of highly paid workers and sending rents soaring. So far, local politics in most of these cities have not allowed the construction of new housing supply to accommodate the increased demand (though some have done much better than others).

So the population problem in the U.S. is highly location-specific. Instead of keeping immigrants out of the country, the government should focus on sending them to places where the population is stagnant or declining and the economy needs shoring up. The Economic Innovation Group, a think tank, suggests using place-based visas to send skilled immigrants to declining regions. But even low-skilled laborers can bring new life to declining towns across rural America.

By trying so hard to keep foreigners from moving to the U.S., Trump is threatening to sentence the country to demographic decline — and to decreasing relevance, dynamism and power. Embracing the myth that the country is full would be a misstep of historical proportions.

For more Bloomberg Opinion articles, visit http://www.bloomberg.com/opinion.


Noah Smith is a Bloomberg Opinion columnist. He was an assistant professor of finance at Stony Brook University, and he blogs at Noahpinion.

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