A Comparison of the Economic Effects of Immigration Scale in the United States and Japan: An Analysis of the Differences in GDP Growth from the Perspective of Immigration Concentration Degree

Abstract

Based on panel data from 50 U.S. states and 47 prefecture-level regions in Japan between 2006 and 2018, this study employs a year-fixed-effects model to empirically analyze the impact of legal immigration on regional economic growth. After controlling for key variables such as population aging and unemployment rate, the results indicate that immigration size exerts a statistically significant positive effect on regional GDP growth in both countries, with a more pronounced marginal effect in the United States (elasticity coefficient: 0.068) compared to Japan (0.053). Both population aging and unemployment rate significantly hinder economic growth, particularly in Japan, where the adverse effects of demographic aging are especially salient. In terms of model fit, the U.S. sample demonstrates strong explanatory power (R² = 0.906), substantially higher than that of Japan (R² = 0.611). Further heterogeneity analysis based on the degree of migration concentration reveals that the positive association between immigration and economic growth remains stable in Japan, while exhibiting a weakening trend in certain U.S. regions. These findings suggest that migration policy formulation and implementation should be closely aligned with regional economic characteristics to enhance policy effectiveness and adaptability.