We provide an analysis of COVID-19 mortality data to assess the potential magnitude of COVID-19 among prison residents. Data were pooled from Covid Prison Project and multiple publicly available national and state level sources. Data analyses consisted of standard epidemiologic and demographic estimates. A single case study was included to generate a more in-depth and multi-faceted understanding of COVID-19 mortality in prisons. The increase in crude COVID-19 mortality rates for the prison population has outpaced the rates for the general population. People in prison experienced a significantly higher mortality burden compared to the general population (standardized mortality ratio (SMR) = 2.75; 95% confidence interval = 2.54, 2.96). For a handful of states (n = 5), these disparities were more extreme, with SMRs ranging from 5.55 to 10.56. Four states reported COVID-19 related death counts that are more than 50% of expected deaths from all-causes in a calendar year. The case study suggested there was also variation in mortality among units within prison systems, with geriatric facilities potentially at highest risk. Understanding the dynamic trends in COVID-19 mortality in prisons as they move in and out of hotspot status is critical.