What is controversial is the nature of the impact of internal migration on regional rates of growth of per capita income and on regional inequality in per capita income. Gunnar Myrdal has argued that migrants tend to be in the most productive ages, and that therefore the regions receiving migrants benefit economically, while the originating regions are harmed. Because it is the advanced and expanding regions which are usually the receiving regions, internal migration, according to Myrdal, widens the gap in per capita income between the advanced and the poorer regions.2 On the other hand, for a specific case, Richard A. Easterlin has concluded that in the United States since 1880 the important forces in the convergence of per capita income levels ... [has] been the inter-regional migration of persons ..., Elsewhere, it has been shown that it is impossible on theoretical grounds to be certain of the effect on inequality of internal migration: it is necessary to consider the economic and demographic structures of the regions, whether or not the more rapidly expanding regions are also the advanced regions, and whether the time horizon is long-run or short-run.4 The main purpose of this article is to present two econometric models constructed primarily with a view towards examining the effect of interstate migration on the inequality of per capita income among the states. Important auxillary questions will also be explored. The models are fitted with United States data for the period 1940 to 1950. Although our findings may apply to the United States for other decades, as well as to other advanced countries, further research is required to ascertain this. The period was one when, as a result of the war and its after-effects, labor