Standard estimates of the illegal/undocumented immigrant population in the United States range from about 11 million to 15 million. But right-wing immigration restrictionists often assert the true figure is much higher, as with Donald Trump's claim that it is 25 million. The implicit assumption is that the higher the number, the stronger the case for mass deportation. But, as my Cato Institute colleague David Bier - a leading immigration policy expert - explains in a recent article (fuller, but paywalled version here) the exact opposite is true:
The math is simple. The more illegal immigrants, the more Americans would have to pay to deport them. The Department of Homeland Security estimates that a single deportation costs on average $18,245. This means that when Trump invents the presence of 10 million more immigrants, he's adding a theoretical $182.4 billion to the price tag.
And that's just the cost of deportation. The cost to federal revenue is even starker. Illegal immigrants pay sales tax — and, often, Social Security tax, income tax and property tax. The more illegal immigrants we deport, the more the cost of funding government would shift to American citizens and legal residents. The Congressional Budget Office estimated that recent illegal immigrant arrivals would have cut deficits by nearly $1 trillion over 10 years, and found that Trump's crackdown in 2025 had already erased $500 billion of those savings.
Illegal immigrants receive very few taxpayer benefits because they are ineligible for all the largest federal public benefit programs, and most states also restrict eligibility for smaller state programs. Since the benefits being paid are a known quantity, a larger illegal immigrant population suggests that the cost per immigrant is actually far lower than we think.
But the taxpayer expenses are dwarfed by the broader economic impact: less stuff produced for the American people. The Peterson Institute for International Economics has estimated that just 8.3 million deportations would leave U.S. gross domestic product 7.4% lower than otherwise by 2028, the equivalent of about $2.5 trillion. Lower output means fewer goods and services — everything from food to childcare — for Americans.
