Japanese immigration to the continental United States was concentrated during the years 1900?1920, and was always governed by changing legal restrictions and relations between the two nations. As the population and success of Japanese communities grew in the United States, so did the racial prejudice against them. The anti-Japanese campaigns began with racial stereotypes and propaganda, and became institutionalized into laws that denied Japanese citizenship and prohibited property ownership.

Japan's spectacular victory over Russia in the war of 1904?05 was the first defeat of a European power by an Asian nation in modern times. This victory stimulated national and racial pride among Japanese everywhere. Among white people in the United States, the rise of Japan on the world scene and a tradition of racial prejudice against Japanese led to fears of a future "yellow peril" and to predictions of an eventual war.

In 1938, Gum Inc. of Philadelphia began issuing a series of bubble-gum cards entitled "The Horrors of War," prepared by George Maull, a Sunday-school teacher and the firm's advertising counsel. Commenting on the cards, a Life magazine writer noted that: "Some future historian may trace a cause for a future U.S.-Japanese war to the fact that pre-adolescents in America received severe anti-Japanese prejudices through its curious liking for blowing bubbles with...gum."

Opponents of Japanese immigration had long contended that Asian immigrants were ineligible for naturalized citizenship. This claim rested on state and municipal laws that restricted naturalization to free whites and aliens of African descent — language based on an act of Congress from the 1790s. In a 1922 ruling, Ozawa v. U.S., the U.S. Supreme Court upheld a Hawaiian statute that denied Japanese immigrants citizenship on these grounds. Following this, the Asian Exclusion Act of 1924 ended further Japanese immigration for permanent residence.

By 1940, in spite of prejudice and legal restrictions, Japanese Americans had established firm roots in the United States. Although Issei immigrants were prohibited from becoming citizens and owning property, many owned homes, farms and businesses held in the names of their children born in America, who were automatically U.S. citizens and therefore eligible to own property.