Spatiotemporal analysis uncovers eight distinct population change trajectories across U.S. counties from 1950 to 2020, highlighting regional demographic polarization.
In recent decades, the United States has experienced substantial changes in population size, composition, and distribution. As growth has slowed, population loss has taken on increased salience, presenting an emerging social, economic, and political challenge and highlighting a need for measures that capture the reality of disparate local population change trajectories. In this article, we use sequencing and clustering algorithms, paired with contemporary and historical U.S. county-level population data (1950–2020), to show the value of incorporating spatial and temporal context in measures of population change, develop a typology of change trajectories, and evaluate observed pathways of loss and growth. Our analysis identifies eight distinctive pathways of population change, ranging from emerging localized loss to constant growth. Most pathways are associated with particular geographies (e.g., “persistent loss” counties dominate the landscape of the Great Plains region), illustrating the spatial polarization of the U.S. demographic experience. A comparison of population composition and components of change further reveals notable differences in demographic characteristics across different types of loss and growth counties.
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Park et al. (2026) studied this question.
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