<p>Mass shooters commit some of the most extreme crimes in the United States, their attacks are almost always premeditated, and their guilt is almost never in doubt. However, they rarely receive the death penalty. To learn more, we examined the frequency of various outcomes for public mass shooters who attacked from 1966 to 2023 (<i>n</i> = 190), along with factors that could explain sentencing differences and changes over time. Our findings suggest only 12% of all U.S. mass shooters received a death penalty sentence, but more than 40% who made it to adjudication and were eligible got that sentence. Unexpectedly, the most heinous mass shootings were not significantly more likely to result in death penalty sentences, and most demographic, aggravating, and mitigating factors were similarly common among shooters who were and were not sentenced to death. Overall, state politics and guilty pleas were most closely associated with sentencing differences, but over time, fewer mass shooters were sentenced to death in both blue states and red states. The change in red states indicates a major reversal from prior decades.</p>