President Donald Trump has adopted a blunt new message for migrants seeking refuge in the United States: “Our country is full.”

To the degree the president is addressing something broader than the recent strains on the asylum-seeking process, his line suggests the nation can’t accommodate higher immigration levels because it is already bursting at the seams. But it runs counter to the consensus among demographers and economists.

They see ample evidence of a country that is not remotely “full” — but rather one where an aging population and declining birthrates among the native-born population are creating underpopulated cities and towns, vacant housing and troubled public finances.

Local officials in many of those places view a shrinking population and workforce as an existential problem. “I believe our biggest threat is our declining labor force,” said GOP Vermont Gov. Phil Scott in his annual budget address this year. “It’s the root of every problem we face.

“This makes it incredibly difficult for businesses to recruit new employees and expand, harder for communities to grow and leaves fewer of us to cover the cost of state government.”

Or if you look at a city like Detroit, “many of the city’s problems would be eased if its population would start growing,” said Harvard economist Edward Glaeser. “All sorts of things like the hangover pension liability become much more solvable if you’re actually looking at new people coming in.”

The Congressional Budget Office foresees the U.S. labor force rising by only 0.5 percent a year over the coming decade, about one-third as fast as from 1950 to 2007. That is a crucial reason that economic growth is forecast to remain well below its late 20th-century levels.

And that, in turn, is reflected in the national fiscal outlook. There are now 2.8 workers for every Social Security recipient, a rate on track to fall to 2.2 by 2035. Many state pension plans face even greater demography-induced strains.

In smaller cities and rural areas, demographic decline is a fundamental fact of life. A recent study by the Economic Innovation Group found that 80 percent of U.S. counties, with a combined population of 149 million, saw a decline in their number of prime working-age adults from 2007 to 2017.

U.S. population growth has now hit its lowest level since 1937, partly because of a record-low fertility rate.

“That immigrants keep showing up here is a testament to our freedom and the economic opportunity here,” said Matthew Kahn, a University of Southern California economist. If immigrants weren’t trying to come — if they believed the United States to be full — that would be a problem, Kahn said.