A number of digital projects have been implemented for archival and special collections. The amount of funds and effort devoted to such projects is enormous, and now they are providing greater opportunities and convenience for researchers to view and make use of important, rare, and/or brittle historical materials. However, little attention has been paid in the information science field as to how much impact these projects to digitalize archival collections have had on actual historical research publications. Existing studies are largely devoted to system designs and the user/usability interface, as well as users' search behaviors. Little has been done to determine the direct relationship between digital resources and historical research. This study surveyed research articles in the field of history to observe how frequently and widely digital collections were used, what kinds of digital collections were used more extensively and for what purposes, and what the current status of digital archival collections among other resources is in historical research. Citations and figures in articles of the American Historical Review for the period 2001–2010 were analyzed with a specific focus on digital archives collection. The usage patterns by material types and formats of references and the impacts of digital archival collections among other sources are identified from two perspectives of impact: intensity and extensity. Observation of the direct relationships with digital collections and historical studies suggest some practical guidelines for future digital projects with concrete data.