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The Delphi method is an iterative, anonymous, group-based process for eliciting and aggregating opinion on a topic to explore the existence of consensus among experts. The year 2023 marks the 60th anniversary of the first peer-reviewed journal article on the Delphi method. Originally developed for operations research, this method is now applied extensively by researchers representing diverse scientific fields. We used a bibliometric analysis to describe general trends in the expansion of its use across disciplines over time. We conducted a systematic literature search for all English-language, peer-reviewed journal articles on the Delphi method through its first 60 years. We found 19,831 articles: 96.8% (n = 19,204) on the actual use of the Delphi method in an empirical study and 3.2% (n = 627) describing, examining, or providing some guidance on how to use the Delphi method. Almost half (49.9%) of all articles were published in the 2010s and an additional third (32.5%) in the first few years of the 2020s. Nearly two-thirds (65%, n = 12,883) of all published articles have appeared in medical journals, compared to 15% in science and technology (n = 3,053) or social science (n = 3,016) journals. We conclude that the expanded use of the Delphi method has been driven largely by the medical field, though social scientists and technologists continue to be at the forefront of methodological work on the Delphi method. Therefore, we call for greater transdisciplinary collaboration on methodological guidance and standards for the Delphi method.