Assessing the Longitudinal Relationship Between Crime and Medical Marijuana Dispensaries

Introduction. Medical marijuana dispensaries continue to attract attention by the popular press for their perceived effects on local communities. One of the biggest concerns has been about how availability of marijuana through store-front dispensaries will affect crime rates in local areas. The current study will look at how changes in dispensaries over a two year period affects violent, property, and assault crimes in Long Beach, California. During this time period, local law enforcement conducted a series of operations designed to reduce or eliminate the number of store-front medical marijuana dispensaries in the city providing a natural experiment with which to study the relationship of crime and dispensaries.

Methods. Data were collected from 336 Census block groups for the Long Beach, California over 24 months (January 2012 to December 2013) for a total sample size of 8064 (n = 336 * 24). Crime data were obtained from the Long Beach Police Department and geocoded to point locations. Locations of store-front medical marijuana dispensaries were obtained from websites (e.g., weedmaps.com) and official city registration lists. These locations were visited every other month to verify whether or not the dispensaries were actually open. Data were analyzed using Bayesian space-time models.

Results. The density of dispensaries within a block group were not related to crime rates during the 24 month study period.  However, density of dispensaries in adjacent areas (as defined by those block groups that shared a boundary were related to higher rates of crime for assaults, property, and violent crimes.

Conclusions. The results of this study suggest that crime displacement may be occurring. In other words, dispensaries do not increase crime in local areas, but having dispensaries in an adjacent block group does increase crime locally. States and local jurisdictions that allow medical marijuana dispensaries will need to assess how effects related to crime displacement can be mitigated.