Heterogeneity in the rise and decline of city-level homicide rates, 1976-2005: A latent trajectory analysis

This study applies latent trajectory methods to the analysis of temporal changes in homicide rates among large US cities across recent decades. Specifically, annual homicide rates for 157 large US cities are analyzed for the 30 years from 1976 to 2005. We address the fundamental questions: Did all of cities experience similar levels and patterns of rise and decline in homicide rates over these three decades? Or is there hidden or unobserved heterogeneity with respect to these temporal patterns, thus leading to the identification of more homogeneous groupings of the cities? And if latent homogeneous groupings surface, is membership due to specific structural characteristics found within those cities? Evidence is found for the existence of four latent homicide rate trajectories. After identifying and classifying the cities into these four groups, multivariate statistical techniques are used to determine which social and economic characteristics are significant predictors of these distinct homicide trends. Criminal justice measures are also included as controls. It is found that larger cities located in the South with higher levels of resource deprivation/concentrated poverty, higher income inequality, higher percentages of the adult male population that are divorced, higher unemployment rates, higher percentages of youth, higher percentages of the population who are Hispanic and higher numbers of police per capita are more likely to be in a higher than a lower homicide trajectory group. Higher percentages of the population enrolled in colleges and universities and locations in states with higher incarceration rates are characteristics of cities associated with membership in a lower homicide trajectory group.