The Puerto Rico Citizenship Archives Project (PRCAP) is a public repository designed to document the legal history of the extension of U.S. citizenship to Puerto Rico. The PRCAP provides a comprehensive overview of 119-year history of debates over the extension of citizenship to Puerto Rico. It also provides public access to the key historical documents shaping this story. The main goal is to create a reliable public archive of primary documents that can foster new research projects on Puerto Rico and its relationship to the United States as well as on broader visions of U.S. citizenship.