The primary objective of this study is to present an explanation of the interstate migratory movements of white and nonwhite persons which occurred over the period 1955–1960. The study is similar to several other recent studies in that we estimate the magnitudes in which various factors have influenced interstate or interregional migration in the United States. It differs from earlier studies in two important respects. First, we estimate and compare the magnitudes in which certain factors have influenced both white and nonwhite interstate migration. Second, unlike previous studies, many of which have made “country-wide” estimates of the determinants of migration, we have disaggregated data to the state level and obtained white and nonwhite “migration elasticities” for every state. These elasticities are in turn used to test several additional hypotheses relating to racial and regional differences in the elasticities themselves. We argue that discrimination against nonwhites and/or differences in “social milieu” between South and nonsouth provide a unifying explanation for most of the observed differences in white and nonwhite migration elasticities.