Based on the “Yearbook of Immigration Statistics” published by the United States Department of Homeland Security and the Global Migration Stock Database released by the United Nations Department of Economic and Social Affairs, this paper systematically analyzes the scale, structure, origins, and destinations of international migration to and from the United States from 1990 to 2020. The study finds that the scale of international immigration to the United States is significant, having gone through four phases over the past 30 years: decline, rebound, fluctuation, and decline again. The immigrant population mainly consists of people of working age, with a stable gender ratio. North America (excluding the United States) and Asia are the primary sources of immigrants to the United States. Additionally, the top ten countries and regions of origin for immigrants have remained relatively stable. On the other hand, international emigration from the United States has experienced three phases over the past 30 years: increase, decrease, and rebound. The gender differences in the emigrant population are generally small but vary significantly across different regions. Europe and North America remain the primary destinations for American emigrants, but an increasing number of Americans are emigrating to Asia. The patterns and governance of international migration in the United States have multiple implications for China.