The Greater the Illegal Migrant Population, the Stronger the Case Against Mass Deportation

Immigration Cato Instiute immigration expert David Bier explains why. | 8.18.2026 6:01 PM People hold up "mass deportation now" signs at the 2024 Republican National Convention. (Carol Guzy/ZUMAPRESS/Newscom) 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) demonstrates in a recent article (fuller, but paywalled version here) the exact opposite is true: The math is simple. The more illegal