Jurisdictional reliance on the death penalty continues to be shaped by broad socioeconomic factors, but the relationship between these factors and the use of the death penalty are more complex than suggested by previous state-level analyses, according to a new study that utilized sweeping county-level data. 

The study, published April 12 in Criminology, found that the degree of public support for Republican presidential candidates in counties is directly associated with greater reliance on the death penalty. Counties with larger Protestant fundamentalist populations impose death sentences to a greater degree, on average, and the size of economically marginalized populations within counties is directly related to a greater reliance on the death penalty over time.

In contrast to prior studies, though, there was no evidence that the size of a county's African American population was directly related to local reliance on the death penalty. Rather, the analysis found that the size of African American populations influenced jurisdictional use of the death penalty indirectly via the size of unemployed populations, and so the size of unemployed populations mediated the previously observed relationship. 

Ethan Amidon, the lead author of the paper and an associate professor at Missouri State University, told The Academic Times that he became interested in this topic during graduate school, but at that time, it was not possible to examine the effects of political, social and economic considerations on the death penalty at the county level because of a lack of publicly available data. 

Instead, prior research focused on social, political and economic relationships vis-à-vis the death penalty at the state level, but once county-level data was made available by individual researchers and organizations, including the Death Penalty Information Center, Amidon and his colleague, John Eassey of American University, set out to examine potential factors that influence county-level use of the death penalty. 

The United States' national reliance on the death penalty has shifted from a late 20th-century peak of 330 death sentences in 1994 to 32 death sentences in 2016, according to the study. Despite this national decline, however, researchers have found social, political, and economic relationships with the use of the death penalty — such as political affiliation, religious sentiment and socioeconomic status — that still persist today. These relationships are more complicated when examined at the local level as opposed to the state level, Amidon said.

Amidon and Eassey examined county-level political factors associated with the imposition of death sentences from 1990 to 2010; they begin in 1990 because consistent information on capital punishment was not available for all counties until this time. 

The final sample consisted of 7,323 county-years from 2,572 jurisdictions across three measurement periods — one for each of the three studied decades. Reliance on the death penalty was measured by examining the number of times the punishment was imposed across counties; this data was obtained from prior research that contains county death sentences from 1991 to 2017. The researchers also controlled for factors that would influence the analysis, such as the number of homicides within counties, using the FBI's Crime in the United States publications.  

The researchers found that jurisdictions where support of "tough on crime" Republican presidential candidates grew over time were slower to move away from the use of the death penalty. A one standard deviation increase in the partisan politics variable — measured by using the percentage of the vote for Republican presidential candidates in counties — was associated with an expected 31% increase in the number of death sentences within counties over time.

They also found that the size of Protestant fundamentalist populations was associated with the use of the death penalty between counties, with a one standard deviation increase in the percentage of religious fundamentalists being associated with an expected 38.4% increase in the number of death sentences across jurisdictions. 

The size of a county's unemployed population was also associated with a higher likelihood of using the death penalty, but in contrast to prior studies, Amidon and Eassey found that reliance on the death penalty begins to diminish once the number of unemployed people reaches a certain threshold. 

The researchers wrote that reliance on death sentences "initially increases as the size of the unemployed population increases. When the size of this group reaches approximately 1.25 standard deviations above the mean, however, or between the 89th and the 90th percentile in the distribution, the relationship becomes negative."

When it came to African American populations, Amidon said he was surprised to find that the size of unemployed populations mediated the relationship between the size of African American populations and a county's use of the death penalty. 

"In other words, we found that the size of African American populations influenced jurisdictional use of the death penalty indirectly via the size of unemployed populations, " he said. "This result is interesting because most prior state- and county-level studies have found a direct relationship between the size of African American populations and jurisdictional reliance on the death penalty."

The findings of this study provide support for arguments that the nature and severity of penal punishment practices are shaped by the broader social, economic and political landscapes in which they take place, according to Amidon. This study was an important step in testing these theories at the county level, Amidon said, with more research necessary to further investigate the local political determinants of the death penalty. 

"As more researchers continue to expand on the death sentences [data] that are currently available," he said, "I am sure that we will develop a more thorough understanding of the political factors associated with local reliance on the death penalty."

The study "Examining the county-level political considerations associated with declining reliance on the death penalty from 1990 to 2010," published April 12 in Criminology, was co-authored by Ethan Amidon, Missouri State University; and John M. Eassey, American University.