More people are moving out of the U.S. than moving in for the first time since the Great Depression—a bad omen for the $38.8 trillion national debt

Net international migration to the U.S. peaked at 2.7 million new entries in 2024, but has since sharply declined. It fell to 1.3 million last summer, according to January census data, and then turned net negative, according to research from Brookings, meaning more people are leaving the U.S. than coming in. The private sector has weighed in too, with Goldman Sachs economists reporting last week that immigration policies put in place over the past year have resulted in an 80% decline in net migration relative to the historical average.

It isn’t just celebrities like George Clooney packing up for France. Places like Portugal, Spain and the Netherlands have seen American expat populations double lately, and Germany and Ireland both received more American arrivals last year than the other way around.

Negative net migration hasn’t definitively happened in the U.S. for almost a century, not since the Great Depression. The U.S. native-born population is also in free fall, well below the replacement rate needed to maintain population numbers in the long run. With fewer immigrant arrivals already dealing a blow to the workforce, the shrinkage of the American taxpayer base is set to further widen the country’s deficit and hurt its prospects for economic growth.

“At a time when native-population growth is slowing due to persistently low fertility rates, declining immigration is poised to weigh heavily on labor supply, debt sustainability, and long-term economic growth, with negative effects likely to emerge even in the near term,” researchers at the Deloitte Global Economics Research Center wrote in an analysis published Friday.

A deeper debt hole

The report pointed out how birth rates in the U.S. have been below the minimum replacement rate since 2008, meaning that the bulk of population growth since then has been due to immigration. This has been especially true for the country’s labor force. Nearly 80% of immigrants are of working age, according to the census, and they account for 19% of the workforce, around 33 million people.

In his first year back in office, Trump has cracked down on immigration by narrowing legal pathways for migrants, restricting visa processing for nationals of 75 countries, and enacted sweeping deportation campaigns in U.S. cities.

Those actions could have severe repercussions on the U.S. economic trajectory. The Deloitte report noted how a projected rise of 8.7 million immigrants over a five-year period starting in 2024 translated to a 2.9% surge in GDP, citing numbers from the Congressional Budget Office.

But if net immigration to the U.S. stays in the red, the primary long-term would be fiscal in nature, as a shrinking workforce will do no favors to the country’s national debt. The Deloitte researchers wrote that immigration tends to have a “positive effect on the federal deficit, allowing revenue to rise faster than expenditure.” 

The data so far largely bears this out. Immigrants contributed more than $650 billion in taxes in 2023, according to the American Immigration Council, an advocacy non-profit. On a per capita basis, those receipts likely eclipse the contributions of non-immigrants. A recent white paper by the Cato Institute, a libertarian think tank, analyzed years’ worth of tax receipts and government expenditure between 1993 and 2023. It found that immigrants, both documented and undocumented, contributed vastly more in taxes than they received in benefits at the local, state or federal level. In total, Cato found, immigrant taxpayers resulted in $14.5 trillion as fiscal surplus over the period studied. 

Because immigrants are likely to be of working age and employed, they also paid nearly $100,000 more in taxes than the average native-born American, the study found. In their absence, national debt would be at around 200% of GDP, rather than the current roughly 120%.

“Immigrants, just by showing up, they’re reducing the debt-to-GDP [ratio], and that’s a good thing for the country,” David Bier, Cato’s director of immigration studies and one of the report’s coauthors, previously told Fortune.

Wiping out a ‘fiscal engine’

Runaway immigration can have its economic downsides. The Deloitte report noted that a large and sudden influx of immigrants can strain local and state-level budgets, while some research has found that immigration waves can lead to a short-term rise in housing prices. A 2025 Penn-Wharton analysis of the economic effects of Trump’s sweeping deportations also reported some potential wage benefits. It found that a 10-year campaign targeting unauthorized immigrants could lead to a 5% wage gain for low-skilled authorized immigrants and native-born Americans due to less competition.

But the majority of the economic literature points to these drawbacks being eventually mitigated by the economic upsides to immigration. Higher housing prices are usually offset by increased supply due to many immigrants joining the construction industry. And the greater GDP growth that usually accompanies immigration can actually raise native-born wages, the Deloitte researchers noted, by boosting overall productivity. 

Even the Penn-Wharton study added a caveat to its finding that deportations might raise low-skilled wages: High-skilled workers, who make up nearly two thirds of the U.S., would likely see their own wages decline because they rely on low-skilled labor to maximize their productivity, according to its analysis.

As for the national debt, the benefits of immigration are only likely to accrue with time. Later generations of immigrants tend to pay more in taxes as educational attainment and incomes rise, according to the Cato Institute’s report, which called children of immigrants “the most potent fiscal engine this country has ever seen.” Should Trump’s immigration crackdown cause a sustained decline in new entries, that engine will be much less powerful than it could have been.