Time-series analysis of clusters in city size distributions.

Complex systems, such as urban systems, emerge unpredictably without the influence of central control as a result of adaptive behaviour by their component, interacting agents. This paper analyses city size distributions, by decade, from the south-western region of the United States for the years 1890–1990. It determines if the distributions were clustered and documents changes in the pattern of clusters over time. Clusters were determined utilising a kernel density estimator and cluster analysis. The data were clustered as determined by both methods. The analyses identified 4–7 clusters of cities in each of the decades analysed. Cities cluster into size classes, suggesting variability in growth rates at different scales. [ABSTRACT FROM AUTHOR]