Immigration has been a core, and often controversial, aspect of the United States since the nation’s inception. All Americans, excepting those of complete Indigenous ancestry, are descendants of immigrants, and for this reason, the United States has always had unique cultural ties to other countries.

Immigrants are often the only exposure to another culture that natives of a country receive, and for better or for worse, immigrants often shape how their home country is seen in their new land. However, immigration, and the resulting cultural and ethnic ties between the US and other countries, are not usually studied by historians of foreign relations even though immigration plays a role in shaping foreign policy. The interplay between immigration and international diplomacy can be crucial, as the example of the relations between the United States and Japan between 1900-1930 reveals.  At the turn of the century, the United States and Japan enjoyed cordial relations, but some thirty years later, the two countries were openly hostile towards one another. What accounts for this change? Some scholars at the time such as William L Holland, executive secretary and editor of the Far Eastern Survey, and Ellen Churchill Semple, the first female president of the Association of American geographers, claimed that pure geographical and demographical realities created this downturn in Japanese-American relations. However, their argument is incomplete and underestimates a more fundamental component: racial attitudes. American immigration policy, forged by changing and increasingly racist attitudes towards the Japanese, contributed to hostile relations between Japan and the United States. Racially motivated immigration policy catalyzed the decline of Japanese-American relations as proven by the impact of three events: racist school policies in 1906 San Francisco impacting national decisions, President Woodrow Wilson’s refusal to accept a racial equality clause in the charter of the League of Nations in 1918, and the Asian Exclusion Act of 1924.