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

TL;DR

This paper presents a detailed hierarchical regionalization of over 3,000 U.S. counties based on migration flows, including both ordinal and cardinal dendrograms, enabling better exploration of regional structures.

Contribution

It provides a county-searchable dendrogram of U.S. counties based on migration data, with both ordinal and cardinal scales, enhancing interpretability and accessibility of the regionalization.

Findings

Hierarchical regionalization of 3,107 counties based on migration flows

Introduction of a county-searchable dendrogram for detailed inspection

Comparison of ordinal and cardinal dendrogram scales

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.