The objectives of this study are twofold. First, a simultaneous-equations model that takes into account the interactions between various economic aspects of urban growth and migration to and from urban areas is specified. Second, the model is estimated for two different time periods, 1950–60 and 1960–70, with the Standard Metropolitan Statistical Area as the basic urban geographic unit. Included among the jointly dependent variables are civilian labor force out-migration, civilian labor force in-migration, income change, manufacturing employment change, government employment change, other nonmanufacturing employment change, and unemployment change. Significant interactions among the various endogenous variables are uncovered for both time periods studied.