This article examines the determinants of interprefectural patterns of Japanese emigration to the U.S. Pacific Northwest, using a multiple regression analysis. In estimating the regression equations, new proxies are introduced for the “family- and-friends” effect that are free of the statistical problems common in previous studies on long-distance migration. The result shows that the information networks that developed between pioneer immigrants and their home districts played a central role in shaping emigration patterns. The lack of an alternative means of obtaining reliable information about conditions in the United States appears to be responsible.