If we passed a law saying it’s illegal for people born in New York to move to California or vice versa, that would make most New Yorkers worse off. It would also make most Californians worse off. But importantly, the negative impact of introducing that kind of inefficiency into the labor market would be felt even more widely as the newly impoverished versions of New York and California would have a generally deleterious impact on the national economy.
The typical individual who migrates from a poor developing country to the United States sees an increase in income by a factor of four, largely as a result of the immense international differences in labor productivity that exist in the world today. As an illustrative example, I estimate that migration from Mexico to the United States raises global income by an amount equivalent to roughly one percent of US GDP.
Many people purport to be saddened by the fact that so many people live in countries that are poor, tyrannical, or otherwise malgoverned. And rightly so. But relatively few seem willing to acknowledge that one of the simplest and most effective means at our disposal for addressing these concerns is to make it easier for the residents of such countries to move to richer and better-governed places.