Age articulation of U.S. inter-metropolitan migration flows

A fundamental divide in migration research has existed between aggregate studies of movement among geographic regions and micro studies of individual migrant behavior. Micro-scale studies have highlighted the importance of stage of life-cycle in predicting movement propensities, whereas many aggregate studies have focused on age-aggregated data summed over all origins for in-migration and over all destinations for out-migration. In this paper we show that if data for functional metropolitan-centered regions are employed, and if origin-destination specific streams of movement are analyzed, the age-specific patterns of inter-metropolitan migration within the United States cluster into distinctive patterns of flow representative of key stages of the life-course. In order to expose and portray a rich, age-articulated geography of U.S. migration we aggregate county-to-county migration flow data from the 1990 census for extended metropolitan regions: Bureau of Economic Analysis (BEA) Economic Areas. We calculate destination-specific out-migration rates broken down into 17 age groups for each origin-destination-specific migration stream between pairs of Economic Areas and present the results of a factor analysis of these flow-specific age profiles. We use the factor scores to cluster the very large number of origin-destination-specific age profiles and find that seven characteristic types emerge reflecting key mobility stages of the life course. We analyze the distinctive characteristics of the migration flows in each cluster and based on the prevalence of flows of each type within streams of gross in- and gross out-migration we present a typology of the 172 BEA Economic Areas. Our conclusion is that better understanding the age articulation of origin-destination-specific flow patterns would help advance regional science migration research.