We review statistical patterns of the geographic distribution of US executions, compare them to homicides, and demonstrate extremely high degrees of concentration of executions in the modern period compared to previous historical periods. We further show that this unprecedented level of concentration has been increasing over the past 20 years. We demonstrate that it is virtually uncorrelated with factors related to homicides. Finally, we show that it corresponds to a statistical distribution associated with “self-reinforcing” processes: a power-law or exponential distribution.

These findings stand whether we look at individual counties within death-penalty states, across the 50 states of the United States, or look at the international distribution of executions across countries in recent years. The substantive conclusion from the statistical patterns observed is that these cannot be explained merely by random variation around some general average. Rather, localities start down a path, then are reinforced in their pathways. There appears to be little to no logic about why certain counties are the high-use counties, whereas the vast majority have never executed a single individual in 40 years of experience with the modern death penalty, often in spite of thousands of homicides. Our research indicates that a main determinant of whether an individual will be executed is not the crime they commit, but the jurisdiction’s experience with executing others. This is not acceptable—legally, morally, or constitutionally.

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