The US is the world leader in imprisoning immigrants. Its mass immigration detention system emerged as an extension of mass incarceration, rooted in a legacy of racist US immigration and criminal laws. Immigration policy is a structural determinant of health that negatively affects the health of imprisoned immigrants, their families, and their communities. The systemic harms of "detention facilities," which we refer to as "immigration prisons," have been extensively documented, yet incrementalist reforms have failed to result in improved outcomes for immigrants. We argue that ending the practice of immigrant imprisonment is the most effective solution to mitigating its harms. Community-based programs are safer and less expensive than imprisonment, while also being effective at ensuring compliance with government requirements. We identify several priorities for researchers and policy makers to tackle the health inequities resulting from this structurally racist system. These include applying a critical, intersectional lens to studying the policies and practices that drive imprisonment, engaging affected communities in research and policy development, and creating an accountable and transparent system of data collection and release to inform health interventions. The reliance of the US on immigrant imprisonment is a policy choice with immense social and economic costs; dismantling it is critical to advancing health equity.