Objective Analyze the research trends and hotspots in emergency department overcrowding derived from the Web of Science Core Collection database. Methods The Web of Science Core Collection database was utilized as the search data source for the bibliometric analysis, and the associated articles published from January 1, 1990, to October 1, 2023.The search was executed using the following formula: TS = (crowded OR overcrowd OR crowding OR overcrowding) AND TS = (Emergency department). VOSviewer, Scimago Graphicaand and additional tools were utilized for bibliometric analysis, and visual knowledge graphs were created. Results A total of 1869 articles were included in this study. The country with the largest number of publications is the United States. The primary research institution is the University of Toronto. Jesse M. Pines and his group at George Washington University have the greatest influence in the field of emergency department overcrowding research. Carlos A. Camargo is the author with the highest h-index in this field. High-frequency keywords include “length-of-stay”, “impact”, “mortality”, “triage”, “association”, “outcomes”, “time”, “management”, “access block”, and “quality”. The clustering graph reveals that all keywords fall into seven categories. Conclusion We recommend intensifying research on emergency department overcrowding in more developing countries. In the future, the application of emerging technologies in emergency medicine as well as the mental health of emergency patients and medical staff may become research hotspots in this field.