Ordinal and Cardinal Dendrograms Depicting Migration-Based Regionalization of 3,000 + U. S. Counties

Abstract

We have obtained a "hierarchical regionalization" of 3,107 county-level units of the United States based upon census-recorded 1995-2000 intercounty migration flows. The methodology employed was the two-stage (double-standardization and strong component [directed graph] hierarchical clustering) algorithm described in the 2009 PNAS (106 [26], E66) letter (arXiv:0904.4863). Various features (e. g., cosmopolitan vs. provincial aspects, and indices of isolation) of the regionalization have been previously discussed in arXiv:0907.2393, arXiv:0903.3623 and arXiv:0809.2768. However, due to the lengthy (38-page) nature of the associated dendrogram, the detailed tree structure itself was not readily available for inspection. Here, we do present this (county-searchable) dendrogram--and invite readers to explore it, based on their particular interests/locations. An ordinal scale--rather than the originally-derived cardinal scale of the doubly-standardized values--in which groupings/features were more immediately apparent, was originally presented. Now, we append the cardinal-scale dendrogram.