This report simultaneously examines alternative mobility decisions and changes in the demographic determinants of residential mobility over the period 1940-80. Alternative mobility decisions are defined as the choice to move locally, to migrate within a state, or to migrate between states. Determinants of mobility include age, race, sex, and educational attainment. A polychotomous multivariate model of mobility was used to analyze data drawn from the public use microdata samples (PUMS) of the decennial censuses of 1940, 1960, 1970, and 1980. Conclusions include the following: (1) educational attainment promotes migration, but not local mobility; (2) the influence of education declines with age up to age 30; (3) blacks are less mobile and migratory than the rest of the population; (4) there is no discernible time trend in racial differentials; (5) females are slightly more locally mobile than males and less migratory with no apparent time trend; and (6) home ownership has a stronger limiting effect on migration than on local mobility. Statistical data are included on five tables. A list of 42 references and three tables of statistical data on geographic mobility by age, education, and race are appended. (FMW)