The ban on immigration produced unusually well-defined generational groups within the Japanese American community. Initially, there was an immigrant generation, the Issei, and their U.S.-born children, the Nisei Japanese American. The Issei were exclusively those who had immigrated before 1924. Because no new immigrants were permitted, all Japanese Americans born after 1924 were — by definition — born in the U.S. This generation, the Nisei, became a distinct cohort from the Issei generation in terms of age, citizenship, and English language ability, in addition to the usual generational differences. Institutional and interpersonal racism led many of the Nisei to marry other Nisei, resulting in a third distinct generation of Japanese Americans, the Sansei. Significant Japanese immigration did not occur until the Immigration Act of 1965 ended 40 years of bans against immigration from Japan and other countries.