Spillover Effects of Homicides across Mexican Municipalities: A Spatial Regime Model Approach

This paper investigates spatial diffusion patterns of high levels of violence across Mexican municipalities to nearby locations while also exploring the possible effect of increasing law enforcement resources in some regions of the country. Our approach consists of providing a framework based on spatial regime models to address spatial heterogeneity that indicates instability in the structural determinants of homicides. In this context, a distinction is made in relation to the regimes that are analyzed between those municipalities that were exposed to joint operations (‘operativos conjuntos’) and those that were not exposed to the operations. Spatial econometric models were estimated for each regime in light of investigating possible spillover effects arising from the covariates. The results point to differences in regard to the significance, magnitude, and sign of the effects related to some variables according to each spatial regime’s specification. While the direct effects show that socioeconomic variables tend to play an important role in explaining the variation of homicides in the non-joint operation regime, the historical level of homicides and closeness to the U.S. border operate in a more significant way for those municipalities in the joint operation regime. In regard to the indirect effects estimates, a positive and significant spillover effect upon homicide rates is attributed to our law enforcement variable as well as to the proxy variable of informality. These spillover effects are found to be greater in magnitude especially in those municipalities exposed to joint operations.