Background: In recent years, endovascular repair has outpaced open repair of blunt traumatic aortic injury (TAI), calling for updated evaluation of severity grading systems to ensure continued efficacy in guiding clinical decision-making. Methods: A retrospective review assessed all adult presentations of blunt thoracic TAI to a single institution from 2005 through 2018. Associations of severity grade with demographics, presentation variables, intervention, and outcomes were analyzed. Results: Thirty-eight patients were included in the analysis. Repair (all endovascular) was pursued in 20 (53%) patients. By grade, 0% of grade 1, 20% of grade 2, 82% of grade 3, and 0% of grade 4 injuries were repaired. Hospital mortality was 16%, and median hospital length of stay was 18 days (IQR 9, 28). Conclusions: A uniform four-grade severity grading system continues to be useful in guiding clinical management for TAI in an environment that is increasingly utilizing endovascular repair.