ABSTRACT
In the context of the full Ecesis model, the migration component is solved simultaneously with the economic and population models. The accounting system takes as given state level fertility and mortality rates and state-to-state migration flows. The late sixties and seventies, however, have shown a dramatic divergence of state fertility rates. For a given year, the economic model passes measures of economic attractiveness for each state to the Generalized Destination Weighted model which calculates interstate migration. Since General Revenue Sharing funds have been allocated on the basis of population estimates, the Census Bureau has been authorized to estimate migration using Internal Revenue Service income tax returns. Thus, state mortality rates are treated as exogenous in Ecesis. The procedure developed to estimate migration in the Ecesis model is called the Generalized Destination Weighted model. Even this short discussion of migration theories indicates how complex an issue internal migration is. Empirical evaluation of such complex theories requires detailed and accurate data.
