Demographic effectiveness (or efficiency) is a measure of the unidirectionality of migration to and from geographic areas. This author explores the structure of temporal change in the demographic effectiveness of migration in the United States during the 1980s. The analysis is based on a times series of (51 x 51) matrices of state-to-state movements derived from matched income tax forms. A number of hypotheses are explored about how in-migration and out-migration fields wax and wane, thereby giving rise to the overall shifts in demographic effectiveness measured over the period. The results highlight the characteristics of recent (1980 - 88) shifts in US internal migration patterns including net migration reversals from strong net in-migration to strong net out-migration for states with significant energy sectors, the stanching of net out-migration from many states of the American manufacturing belt, the turnaround to net in-migration for all of northern New England, and the continuance of highly effective net in-migration to the sunbelt states of Florida, Arizona, and Nevada.