HRA prepared a comprehensive, updated history of the Portland District of the U.S. Army Corps of Engineers titled Engineering in the Twenty-First Century: A History of the Portland District of the U.S. Army Corps of Engineers, 2000–2015. The history examines the work of the District in the twenty-first century and covers such topics as environmental mitigation, maintenance of aging infrastructure and hydroelectric projects, navigation, and technological changes. HRA’s research included the USACE Digital Library, government publications and reports, scholarly journals, and newspapers. In addition, HRA conducted 17 oral history interviews for the project. Among the individuals interviewed were the current district commander, as well as four former commanders, the deputy district engineer, and numerous senior level employees, including division, section, and branch chiefs.