Geographic differences in U.S. homicide rates have decreased since the 1970s

Since the 1970s, gaps in economic and social wellbeing between Americans living in different regions have grown. Some researchers hypothesize that areas with reduced economic and social well-being would see higher rates of violent crime. For instance, impoverished areas with lower tax bases might receive less police protection, or a lack of job opportunities may lead to greater involvement in criminal enterprises, in which violence can be an effective tool.

However, few studies have systematically examined potential links between geographic economic disparities and geographic disparities in violent crime rates. To address this gap, Boylan analyzed data from the National Center for Health Statistics, comparing homicide rates between the US's 741 commuting zones across both urban and rural areas -- distinct geographic areas within which most residents live and work, with few commuting into another zone.

Boylan found that, since the 1970s, disparities in US homicide rates between US commuting zones have steadily decreased, even while economic and social inequalities increased.

One potential explanation for these findings, as Boylan notes, is that since the 1970s, geographic disparities in policing, incarceration, and the share of the population that is African American has also decreased across the US. He suggests that future research could examine whether any of these factors could have contributed to the decreased disparities in homicide rates.

Alternatively, Boylan suggests, the expected violence-boosting effects of worsening social and economic conditions in some areas might have been mitigated by state, county, and federal law enforcement bodies stepping in to ensure continued prosecution of violent crime, such as in instances when local police departments were disbanded in economically challenged cities.

In contrast to the homicide findings, the researcher notes, geographic disparities in US life expectancies have increased since the 1960s, likely due to state policies that include tobacco taxes and Medicaid expansions.

Dr. Boylan adds: "There is a perception that job losses in the rust belt have led to an increase in inequality in crime. However, I provide empirical evidence that inequalities across different parts of the country in crime have steadily decreased since the 1960s and that this decrease coincides with decreases in disparities in policing, incarceration, and the share of the population that is African American."