Whereas one line of recent neighborhood research has placed an emphasis on zooming into smaller units of analysis such as street blocks, another line of research has suggested that even the meso-area of neighborhoods is too narrow and that the area surrounding the neighborhood is also important. Thus, there is a need to examine the scale at which the social ecology impacts crime. We use data from seven cities from around the year 2000 to test our research questions using multilevel negative binomial regression models (N = 73,010 blocks and 8,231 block groups). Our results suggest that although many neighborhood factors seem to operate on the microscale of blocks, others seem to have a much broader impact. In addition, we find that racially and ethnically homogenous blocks within heterogeneous block groups have the most crime. Our findings also show the strongest results for a multitude of land-use measures and that these measures sharpen some of the associations from social characteristics. Thus, we find that accounting for multiple scales simultaneously is important in ecological studies of crime.

Few studies have explored Louis Wirth's propositions regarding the independent effects of population size and density, due to the conceptual difficulty in distinguishing between them. We directly address this conundrum by conceptualizing these as micro-population density and macro-population density. We propose two novel measures for these constructs: population density exposure to capture microdensity, and a measure of population within a twenty-mile radius to capture macrodensity. We combine the theoretical insights of Wirth with routine activities theory to posit and find strong nonlinear effects of micro-density on crime rates, as well as the moderating effect of macro-density. We find strong evidence of macro social processes for population size, including that (1) its strongest effect occurred for crimes generally between strangers (robberies and motor vehicle thefts); (2) there was virtually no effect for homicides, a type of crime that often occurs among non-strangers. For micro-density, our findings include (1) strong curvilinear effects for the three types of property crime; (2) diminishing positive effects for robbery and homicide; and (3) a strikingly different pattern for aggravated assault. The effects for micro-density are stronger than for macro-density, a finding unexplored in the extant literature. We discuss the implications of these results within the context of Wirth's theoretical framework as well as routine activities theory and suggest ways to extend these findings. © The Author 2013.Published by Oxford University Press on behalf of the University of North Carolina at Chapel Hill. All rights reserved.