Migration Signatures through the Decades: Continuity and Change in Age-Specific Net Migration in U.S. Counties

Kenneth M. Johnson, University of New Hampshire

This research uses newly developed county-level age-specific net migration estimates for 2000-2010 supplemented with longitudinal age-specific migration data spanning the prior fifty years. The research foci are to ascertain whether there are clear longitudinal trends in age specific net migration and to determine if there is spatial clustering in the migration patterns. Analysis confirms the continuation into the 2000-2010 decade of distinct net migration “signature patterns” for many types of metropolitan and nonmetropolitan counties. Though there is temporal variation in the overall volume of migration across the decades, age-specific patterns persist. There is also evidence of spatial autocorrelation in large geographically contiguous regions of net in-migration ( in Florida and the Southwest) and geographically contiguous net out-migration regions (in the Great Plains) that persist over time. The patterns of spatial concentration and fragmentation over time in these migration data demonstrate the relevance of examing spatio-temporal migration change.