The Compendium of US jails: creating and conducting research with the first comprehensive contact database of US jails

Background Millions of people pass through U.S. jails annually. Conducting research about these public institutions is critical to understanding on-the-ground policies and practices, especially health care services, affecting millions of people. However, there is no existing database of the number, location, or contact information of jails. We created the National Jails Compendium to address this gap. In this paper, we detail our comprehensive methodology for identifying jail locations and contact information. We then describe the first research project to use the Compendium, a survey assessing jails' treatment practices for incarcerated pregnant people with opioid use disorder. Results This study sent surveys electronically or in paper form to all 2986 jails in the Compendium, with 1139 surveys returned. We outline the process for using the Compendium, highlighting challenges in reaching contacts through case examples, cataloging responses and non-responses, and defining what counts as a jail. Conclusion We aim to provide tools for future researchers to use the Compendium as well as a pathway for keeping it current. The Compendium provides transparency that aids in understanding jail policies and practices. Such information may help devise interventions to ensure humane, evidence-based treatment of incarcerated people.