immigrated before 1924; some of them desired to return to their homeland. Because no more immigrants were permitted, all Japanese Americans who were born after 1924 were, by definition, born in the U.S. and by law, they were automatically considered U.S. citizens. The members of this Nisei generation constituted a cohort which was distinct from the cohort which their parents belonged to. In addition to the usual generational differences, Issei men were typically ten to fifteen years older than their wives, making them significantly older than the younger children in their often large families. U.S. law prohibited Japanese immigrants from becoming naturalized citizens, making them dependent on their children whenever they rented or purchased property. Communication between English-speaking children and parents who mostly or completely spoke in Japanese was often difficult. A significant number of older Nisei, many of whom were born prior to the immigration ban, had married and already started families of their own by the time the US entered World War II. Despite racist legislation which prevented Issei from becoming naturalized citizens (or owning property, voting, or running for political office), these Japanese immigrants established communities in their new hometowns. Japanese Americans contributed to the agriculture of California and other Western states, by introducing irrigation methods which enabled them to cultivate fruits, vegetables, and flowers on previously inhospitable land. In both rural and urban areas, kenjinkai, community groups for immigrants from the same Japanese prefecture, and fujinkai, Buddhist women's associations, organized community events and did charitable work, provided loans and financial assistance and built Japanese language schools for their children. Excluded from setting up shop in white neighborhoods, nikkei-owned small businesses thrived in the Nihonmachi, or Japantowns of urban centers, such as Los Angeles, San Francisco, and Seattle. In the 1930s, the Office of Naval Intelligence (ONI), concerned as a result of Imperial Japan's rising military power in Asia, began to conduct surveillance in Japanese-American communities in Hawaii. Starting in 1936, at the behest of President Roosevelt, the ONI began to compile a "special list of those Japanese Americans who would be the first to be placed in a concentration camp in the event of trouble" between Japan and the United States. In 1939, again by order of the President, the ONI, Military Intelligence Division, and FBI began working together to compile a larger Custodial Detention Index. Early in 1941, Roosevelt commissioned Curtis Munson to conduct an