This paper examines the extent to which sustenance differentiation— an important dimension of the division of labor—influences the redistribution of the population through net migration in the nonmetropolitan counties of the United States during the 1960s. An ecological explanation of this type is shown to be most viable, even when controls for a number of competing explanations are introduced. The evidence provided in this paper supports the longstanding contention of human ecologists about the influence of sustenance organization on population redistribution.